ELECTRON CLOUD STUDIES AND BEAM SCRUBBING EFFECT IN THE SPS
|
|
- Brittney Merritt
- 5 years ago
- Views:
Transcription
1 EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH European Laboratory for Particle Physics Large Hadron Collider Project LHC Project Report 4 ELECTRON CLOUD STUDIES AND BEAM SCRUBBING EFFECT IN THE SPS J.M. Jimenez, G. Arduini, P. Collier, G. Ferioli, B. Henrist, N. Hilleret, L. Jensen, J-M. Laurent, K. Weiss, F. Zimmermann Abstract The performance of the SPS as LHC injector has been limited, with LHC-type beams, by the electron cloud multipacting for high bunch intensities (>.x protons/bunch). To study in detail the dependence of the electron cloud on the beam parameters (bunch intensity, filling pattern, filling factor ), three strip-detectors have been installed inside dipole corrector magnets. The measuring set-up was completed by shielded pick-ups and by an in-situ secondary electron yield detector installed in field-free regions. This paper presents the variation of the electron cloud activity as a function of the bunch intensity and bunch length, filling pattern and filling factor. The spatial and energy distributions of the electrons in the cloud were studied and the latter compared with results obtained with a conventional retarding field detector. Evidence of the scrubbing effect as a solution to reduce the electron cloud activity is shown in the SPS. Heat load estimations based on the electron cloud intensity and on their energy distributions are given as a function of the bunch intensity and filling factor. The results can be compared with independent direct calorimetric measurements. The implications for the LHC are discussed, in particular heat load extrapolations and a possible start up scenario. To be published in Phys. Rev. Special Topics CERN CH - 2 Geneva 2 Switzerland Geneva, 24 April 2
2 ELECTRON CLOUD STUDIES AND BEAM SCRUBBING EFFECT IN THE SPS J.M. Jimenez, G. Arduini, P. Collier, G. Ferioli, B. Henrist, N. Hilleret, L. Jensen, J-M. Laurent, K. Weiss, F. Zimmermann CERN, Geneva, Switzerland Abstract The performance of the SPS as LHC injector has been limited, with LHC-Type beams, by the electron cloud multipacting for high bunch intensities (>.x protons/bunch). To study in detail the dependence of the electron cloud on the beam parameters (bunch intensity, filling pattern, filling factor ), three strip-detectors have been installed inside dipole corrector magnets. The measuring set-up was completed by shielded pick-ups and by an in-situ secondary electron yield detector installed in field-free regions. This paper presents the variation of the electron cloud activity as a function of the bunch intensity and bunch length, filling pattern and filling factor. The spatial and energy distributions of the electrons in the cloud were studied and the latter compared with results obtained with a conventional retarding field detector. Evidence of the scrubbing effect as a solution to reduce the electron cloud activity is shown in the SPS. Heat load estimations based on the electron cloud intensity and on their energy distributions are given as a function of the bunch intensity and filling factor. The results can be compared with independent direct calorimetric measurements. The implications for the LHC are discussed, in particular heat load extrapolations and a possible start up scenario. STRIP DETECTORS DESCRIPTION Since 998, the electron cloud activity is being studied in the SPS using the pressure gauges and shielded pickups [][2][]. During the shutdown of 2-2, three different versions of strip-detectors (Fig.) have been installed to study independently or simultaneously the spatial distribution and the energy distributions of the electrons in the cloud. In presence of LHC-type beams with high bunch intensities, the electron multipacting takes place in the stainless steel vacuum chamber creating an electron cloud. The collecting copper strips are placed under vacuum and separated from the cloud by a grid which transparency was chosen (7%) to reduce the perturbations to the electron cloud itself by an excessive collection of electrons. The distribution of the holes (Ø 2 mm) has been calculated in order to have a similar transparency over the different channels. The three versions of the strip-detectors installed in the SPS machine were designed for specific measurements: -4 batches of 72 bunches injected from the PS machine, 2 ns bunch spacing, 22 ns batch spacing,.x protons/bunch (.7x ultimate) and 4ns bunch length (4σ) at injection energy (2 GeV). the spatial distribution of the electrons with a resolution of.2 mm is measured with a -channels stripdetector 2, a strip pick-up detector for the energy distributions and a retarding field strip 4 detector to study simultaneously the energy and the spatial distributions of the electrons. Beam B field MBA chamber Holes (transparency 7%) Copper strips Fig.: Schematic view of a strip-detector showing the position of the collecting strips with respect to the beam. In both the strip pick-up and the retarding field stripdetector, three filtering grids placed between the beam pipe and the collecting strips allow the energy distribution measurements. The distribution of the holes of the filtering grids is identical to the holes distribution in the beam pipe wall. The two first grids allow to apply a varying filtering voltage potential, the rd grid close the collecting strips avoids that the secondary electrons generated by the primary electrons coming from the cloud, escape from the detector. The readout electronics (Fig.2) of the strip detectors, based on VME system, include a CPU used to control the whole, a timing unit to synchronise the electronics with the beam cycle and five acquisition cards with 8 channels each. The analogue signals issued from the collecting strips of the detectors are integrated with an interval time which can be adjusted from 2 to 2 ms. The revolution time in the SPS being of 2 µs, the fastest acquisition rate (2 ms) will integrate the signals over 87± turns. At the end of each interval time or integrated time, the outputs of the integrators on each analogue card are multiplexed, amplified if necessary (gain 2), digitised by an 8-bits ADC and stored in a 2 Kbytes Ram memory. Several consecutive intervals are stored in the memories during an acquisition cycle. At the end of the cycle, a CPU reads and transfers the data for treatment and display via an Ethernet connection. 2 width of 4 mm, 2 mm in length rectangular strips (x2mm), square (xmm) 4 width of 4 mm, 2 mm in length, -channels, 2. mm resolution
3 T int.= ms C= nf Strips detector Control Strip Ch Integ Ch 2 Ch Ch 4 AMP ADC RAM Ch MPX C= nf Ch Ch 7 Strip 8 Ch 8 Integ 8 Analog card Strip 2 Integ 42-4 MPX AMP ADC RAM Strip 4 Analog card Fig.2: Strip detector readout electronics CPU Timing Unit Similarly, a decrease of the bunch length by % doubles the electron cloud intensity (Fig.) and a rd central strip appears already at.x p/bunch instead of.x p/bunch for the nominal bunch length (4 ns). The simulations already for 8.x p/bunch predicted the appearance of the rd central strip. The rd central strip disappears rapidly and an attempt of explanation will be given in 2.. Conversely, if the bunch length is increased by %, the electron cloud disappeared (Fig.)..2E-.E- N e- (A/m 2 ) 2.E-2 2.E-2.E-2.E-2.E-.E s/div Fig.: Electron cloud build up signal measured using the -channels strip-detector in field-free conditions. 8.E-4.E-4 4.E-4 2.E-4.E Fig.4: Electron cloud build up signal measured using the -channels strip-detector in a dipole field at the start of the run with a 4 batch-injections. 2 s/div 2 ELECTRON CLOUD OBSERVATIONS AND EFFECT OF THE BEAM PARAMETERS The electron cloud multipacting is driven mainly by the beam parameters and by the secondary electron yield (δ max, Energy of the maximum of the secondary electron yield) of the wall surface. Immediately after the air venting, the threshold of the electron cloud, measured with a single batch-injection, was.x p/bunch in the dipole field regions and.x p/bunch for the field-free. In a dipole field, the appearance threshold of the two lateral strips was.x p/bunch and at.x p/bunch, a rd central strip appeared as predicted by the simulations [4][]. Fig. and 4 show respectively the electron cloud build up in a field-free and in a dipole field region with up to 4 batch-injections and.x p/bunch. The non-flat distribution observed on the field-free signal is due to the angular acceptance of the detectors and to the rectangular shape of the vacuum chamber. 2. Electron Cloud Activity 2.. Bunch intensity and bunch length The electron cloud build up is strongly dependent on the beam potential (bunch intensity and length) which determines the kick to the electrons. As expected, the measurements showed an increase of the electron cloud intensity by a factor of 7 to when the bunch intensity is doubled from.x to.x p/bunch. Fig.: The electron cloud is enhanced by a bunch length decrease (left: -%) and disappears with an increase of the bunch length (right: +%) Filling pattern and filling factor To optimise the injection in the LHC, or 4 batches will be accumulated in the SPS before being injected into the LHC. The measurements made using the pick-ups confirmed that the electron cloud build up during the passage of the 2 nd, the rd and 4 th batch is enhanced by the passage of the preceding batches (Fig.). If the lifetime of the electrons is higher than the 22 ns batch spacing, the surviving electrons created during the previous batch passage enhance the build up during the passage of the following batches. But after the 4 th batch passage and due to the revolution time in the SPS, i.e. 2 µs, the st batch will pass once again after 4. µs. This delay appears to be long enough to loose all the surviving electrons. Fig.7 shows the electron cloud signal as a function of the number of batches injected in the SPS. With batches injected, the total number of electrons is times bigger in the dipole field.x - A/m (~2x e - /m) than in the field-free.x -4 A/m (.x e - /m). The pressure rises in the SPS ring confirmed the larger electron cloud activity in the dipole field regions (arcs). Fig.8 shows a linear increase of the electron cloud activity with the 2
4 number of batches injected with a rate of increase larger in the absence of a magnetic field: 2. instead of in a field-free region. Beam signal e - cloud signal e - cloud signal Beam signal Fig.: Pick-up signals showing the build up during the passage of the 2 nd, the rd and 4 th batch enhanced by the passage of the preceding batches (left). ns batch spacing is not long enough to decouple the build up during the passage of two successive batches (right). N e - (A/m) Dipole field 2.E- 2.E-.E-.E-.E-4 e - cloud intensity in a Dipole field batch 2 batches batches e - cloud intensity in a field-free 4 batches.e-4 4.E-4.E-4 2.E-4.E-4.E+.E Time (ms) Fig.7: Electron cloud build up as a function of the number of batches injected in the SPS. N e - (A/m) Field-free through the slots was accepted and is now in the LHC baseline [7]. During the scrubbing runs (addressed in ), the electron cloud threshold in a dipole field (single batchinjection), increased from.x p/bunch to.x p/bunch. It was expected that the threshold of appearance of the two lateral strips would not change since the position of the two lateral strips depends weakly on the energy of the δ max which decrease from 24 down to 22 ev. The measurements confirmed that the threshold of appearance of the two lateral strips stayed constant, the two lateral strips were visible with batch-injections (Fig.) and their position is similar to the one before the scrubbing (Fig.4) even if the amount of electrons decreased by a factor. d (mm) between lateral strips - -. mm 9 mm Beam axis 2 22 Pumping holes in the beam screen -.E+ 2.E+ 4.E+.E+ 8.E+.E+.2E+.4E+ Bunch intensity (p/bunch) Fig.9: Distance between the two lateral strips as a function of the bunch intensity. 2 2 Ratio to batch slope = x +/-.2 slope = 2. x +/-.2 Build up in field-free Build up in dipole fields electrons Fig.: Picture of the beam screen showing the position of the pumping slots and a schematic view of the slot shielding design to intercept the electrons passing through the slots. (Courtesy of N. Kos) 2 4 Number of batches Fig.8: Enhancement factor due to the number of batches injected in the SPS in a dipole and in a field-free condition. 2.2 Spatial distribution of the electrons The spatial distribution of the electrons in the cloud has been confirmed using a -channels strip-detector which allowed twice the resolution obtained in 2 (Fig.9) and recent simulations fit fairly well the measurements []. At.x and.x p/bunch, the two vertical lateral strips of the cloud will stand on top of the beam screen pumping slots (9 and. mm respectively from the centre) as shown in Fig.9, inducing additional heat load to the cold bore. The decision to insert the pumping slot shielding (Fig.) to intercept the electrons passing.2e-.e- 8.E-4.E-4 4.E-4 2.E-4.E Fig.: Distance between the 2 lateral strips after days of LHC-type beams in a dipole field and.x p/bunch. The effect of a dipole field applied on the detector on the electron cloud appears to be more important below 2 s/div
5 Gauss. In these field conditions, both the electron cloud intensity and the width of the lateral strips increase by 2 and 2 respectively. This dependence at low field is not yet understood. Energy acceptance considerations could be one explanation since at low field, the Lamor radius of the electrons is close to the diameter of the holes of the grid. Below 2 Gauss, the electron cloud disappears if the bunch intensity is below the electron cloud threshold in field-free regions. The influence of the magnetic field is even more spectacular when a transition through Gauss field is applied to the magnet and measured with the stripdetector (Fig.2). The behaviour of the electron cloud at these small dipole field and the possible interferences with the acceptance of the strip-detectors is being investigated. and on the pressure rises induced by the electron stimulated desorption (ESD) mechanism. The energy distributions were measured using two different protocols: in a multicycle mode where a different filtering voltage is applied for each SPS supercycle (~2 s duration) or in a single-cycle mode, where the measurements are made within the same cycle by applying an exponential voltage decay to the filtering grids shortly after the last injection. dn/de (a.u.) Strip pick-up (multicycle measurement) d 2 N/dxdE Strip-detector (single-cycle d2n/dxde meas.-fit) Strip detector Strip pick-up (single-cycle measurement).e-2 4.E-2.E-2 2.E-2.E-2.4 s/div Energy (ev) Fig.4: Electrons energy distribution (dn/de) measured in a dipole field using the strip pick-ups detector in a single and multiple cycle mode and using the retarding field strip-detector..e Fig.2: Spatial distribution of the electrons in the cloud during a magnetic field transition through Gauss..E+.E- Ffree batch Ffree 2 batches Ffree batches Dfree batch Dfree 2 batches Dfree batches Strip pick-up Distribution (a.u.) Field free - Strip pick-ups Field free - Retarding Field Detector (fit) RFD Distribution (a.u.).e-2.e-.e Fig.: Evolution of the spatial distribution of the electrons with the number of batches injected in a dipole field (Dfield) or field-free (Ffree) regions. The correspond to the beam position which was slightly offcentred. Fig. gives the variation of the spatial distribution of the electrons with the number of batches injected and with the presence or not of a dipole field. 2. Energy distribution of the electrons The energy distribution of the electrons in the cloud was measured using the strip-detectors in both the dipole field and field-free conditions and using a conventional retarding field detector in a field-free region. Due to hardware limitations, the electrons with energies below 2 ev could not be measured. However, the impact of this limitation is small (<2%) both on the heat load budget Electron Energy (ev) Fig.: Electrons energy distribution (dn/de) measured in a field-free region using the strip pick-ups in a singlecycle mode and using a conventional retarding field detector (RFD) detector. In the dipole field where most of the electrons are trapped in two vertical lateral strips by the magnetic field, the energy distribution showed a peak of energy between 8 and 2 ev (Fig.4) to be compared with the 8 ev measured in the field-free regions (Fig.). The energy distributions measured by the strip pick-ups are in good agreement with the results given by a conventional retarding field detector and by the recent simulations []. The simultaneous energy and spatial distribution studies showed that most of the high-energy electrons i.e. above 2 ev, are located in the central strip (Fig.). The two lateral strips have electrons with energies below 8 ev. This last observation could explain why the central strip tends to disappear after several hours of LHC-type beam. In fact, the decrease of the secondary electron yield is enhanced by the amount of primary electrons. After a given dose, the amount of electrons produced, i.e. δ SEY above the multipacting threshold is reached earlier for the 4
6 electrons with energies above 8 ev thus causing the extinction of the cloud in the central area. The decrease of the SEY will be addressed in. N e - (a.u.) V - V (exp. Decrease) -8 V - V -7 V - V Filtering potential Fig.: Spatial energy distribution (d 2 N/dxdE) of the electrons measured in a single-cycle mode using the retarding field strip-detector. EVIDENCE OF A SCRUBBING EFFECT IN PRESENCE OF LHC TYPE BEAMS The two scrubbing periods, days of beam in total, gave evidence of a scrubbing effect. All around the SPS ring, both in the field-free and dipole field regions, the pressures decreased by in 4 days, 4 in days (Fig.7). Meanwhile, the thresholds measured with the strip-detector increased in the dipole field, from.x to.x p/bunch and from.x to more than.x p/bunch in the field-free regions. No signal could be detected in the field-free regions after days of LHCtype beams with a 4 batch-injection. The Fig.8 shows the increase of the electron cloud threshold measured with pressure gauges in a field-free region, the behaviour was similar in a dipole field. This threshold increase is also a clear signature of the scrubbing. P / I batch.e-7.e-8.e-9.e-2.e-2 Dipole field (HP) Field free (HP8) Bunch Intensity (x E).E Cumul. time (hours) Fig.7: Pressure decreases both in dipole and field-free regions with the LHC-type beam exposure. The pressures are normalised to the batch intensity (P/I bunch x72xn bacthes ). Similarly, the evolution of the electron cloud activity measured by the strip-detectors throughout the cleaning process showed a decrease by a factor 2 in days in a field-free region (Fig.9) and between to in the dipole field regions (Fig.2). Several parameters measured (pressures, electron cloud intensity, heat load measured by the calorimeters [8][9]) showed that the beam-induced multipacting and thus the 9 - V 2 I Bunch ( p) scrubbing stopped after 4 days in the field-free regions. This observation is consistent with the in situ measurement of the secondary electron yield (SEY), which remained constant after 4 days; the δ max was., also consistent with analytical calculations []. After short periods without LHC-type beams, the SEY drifted up i.e. from. to.7 in two weeks time. However, the initial value was recovered after 4 hours with nominal intensity LHC-type beams with at least batches injected. P/P 2 8.E+7 2 days.e+8 4 days.2e+9 days E+ 2.E+ 4.E+.E+ 8.E+.E+.2E+.4E+ Proton bunch intensity Fig.8: Increase of the electron cloud threshold in fieldfree regions with beam exposure. Single batch-injection and.x p/bunch. N e- (A/m).E-2.E-.E-4.E Cumul. time (hours) Fig.9: Evolution of the electron cloud activity measured by the strip-detectors throughout the scrubbing process in field-free conditions showing a decrease by a factor 2 in days. After a venting to air to reset the detectors and beam pipe surfaces, the scrubbing run was repeated to confirm the results of the st scrubbing run (May 22). Fig.2 confirmed the scrubbing efficiency in both the dipole and field-free regions. The step between the first and second part of the chart appeared after the introduction of a ramp in energy ( GeV). Simultanously, the strip detector showed a lateral displacement of the cloud resulting from a beam orbit displacement. The observed pressure rises are easily explained by the bombardement of nonscrubbed surfaces. The introduction on purpose of a small orbit displacement, to 4 mm with respect to the nominal orbit, produced as predicted, an increase of the pressures ( P/P) by to depending on the chamber shape and position in the SPS ring.
7 N e - (A/m).E-.E-4.E-.E- batch 2 Batches Batches 4 Batches Hours of beam Fig.2: Evolution of the electron cloud activity measured by the strip-detectors throughout the cleaning process in a dipole field conditions..e- Dipole field (HP4) Field free (HP4) nominal bunch intensity; the beam dump is adjusted to stay just below the pressures interlock levels. Subsequently, the delay of the beam dump should be increased to stay continuously just below the pressure interlock levels. As soon as possible, increase the number of batches injected ( or 4) or alternatively, increase the bunch intensity and/or shorten the bunches. Finally, introduce a ramp in energy. If not allowed (cost of operation), alternatively introduce local orbit bumps to create orbit displacements to make a wider scrubbing of the inner walls of the bending magnet vacuum chambers. Appearance of the rd central strip Ramp.E-2 4.E-2.E-2 2.E-2.E-2.E+ N e - (A/m 2 ) Pressures (mbar).e-7.e-8.e-9.e+2 2.E+22 4.E+22.E+22 8.E+22.E+2.2E+2.4E+2 Cumulated dose (protons) Fig.2: Pressure decreases both in dipole and field-free regions with the LHC-type beam exposure. Pressure bump after the introduction of the ramp to GeV. However, the decreases both in dipole and field-free regions confirmed the scrubbing effect SEY coefficient 2.4 /9/2 2: 2.2 8/9/2 4:2 2. 8/9/2 9: 9/9/2 :.8 2/9/2 9:4. //2 8: Electron energy (ev) Fig.22: Evolution of the Secondary Electron Yield (δ) measured in situ with the LHC-type beam exposure. During the 2 nd scrubbing period (Fig.22), the δ max decreased faster indicating a memory effect. The ultimate value of. was achieved by injecting a 4 th batch. This result is consistent with the absence of multipacting with batch-injections or less, in the field-free regions where the SEY detector is installed. During the scrubbing, the multipacting threshold (.) is reached earlier for the electrons with energies above 8 ev and this could explain why the rd central strip disappears prematurely as compared to the lateral strips. The two scrubbing runs allowed establishing an optimised scrubbing run scenario for the SPS. The machine should start with or 2 batches injected at Lateral position (mm) s /Division Fig.2: Small orbit displacement seen by the stripdetectors due to the ramp to GeV after the 4 th batchinjection Σ N e - (A/m) 2 GeV lateral strips (A/m 2 ) 4 GeV central strip (A/m 2 ) 4.E- 4.E-.E-.E- 2.E- 2.E-.E-.E-.E-4..E Time (ms) Fig.24: Variation of the electron cloud signal with the number of batches injected and with the ramp in energy (4 GeV). The dark line gives the intensity in A/m 4. EFFECT OF THE RAMP IN ENERGY At the end of the st scrubbing period, a small ramp in energy was introduced after the 4 th injection; the proton energy was increased up to GeV to check whether or not the scrubbing run should be made at injection energy (costs of operation) or if unexpected enhancement effects will imply going to higher energies. The effect of this small ramp was larger than expected since it induced a small displacement of the orbit (Fig.2) producing pressure rises all around the SPS machine (Fig.2) and a doubling of the electron cloud intensity measured by the strip-detectors (Fig.24). A squeezing of the bunch during the ramp, which implies an increase of the beam potential, and therefore an increase of the electron energies could easily explain the increase of the electron cloud activity. As expected from 2.., the two lateral strips became wider and more N e - (A/m)
8 intense and rd central strip, which disappeared after the scrubbing run, appeared again. Similarly, the pressure variations during the ramp indicate also an increase of the electron cloud activity during the ramp, the dipole field regions being more sensitive than the field-free regions (Fig.2). Despite the negative effect of the ramp and a scrubbing run made mainly with 2 batch-injections, the electron cloud intensity was reduced by a factor of 2 after the 2 nd scrubbing run (Fig.2). P/P HP HP7 HP2 Beam Energy (GeV) Time (s) Fig.2: Pressure variations in dipole (HP, HP2) and field-free (HP7) regions during the ramp in energy up to 4 GeV. N e- (A/m) in a dipole field 2.E- 2.E-.E-.E-.E-4 Before scrubbing run (7) After days of scrubbing, ramp GeV (77) After scrubbing run, ramp 4 GeV (78) Energy (GeV).E Time (ms) Fig.2: Evolution of the electron cloud activity before and after the 2 nd scrubbing run and with a ramp in energy at 4 GeV. HEAT LOADS - SCALING TO LHC The heat load due to the electron cloud was measured directly using two different types of calorimeters: pick-up calorimeters [8] and standard calorimeters with a close geometry [9]. In this paper, only the heat loads calculated from the electron cloud intensity and from the energy distribution of the electrons are presented. This approach is very useful since the strip-detectors provide a fast response (a few seconds) as compared to the close geometry calorimeters, which have an intrinsic time constant of a few hours. The pick-up calorimeters are an intermediate solution with a time constant of 2 minutes. But due to their overall size, these pick ups cannot be installed in dipole field regions. As stated earlier ( 2.), the energy distribution of the electrons below 2 ev could not be measured. The Beam Energy (GeV) Beam energy (GeV) contribution of the low energy electrons (<2 ev) on the heat load was measured by applying a bias voltage (-V) on the collecting plates of the pick up calorimeters to repel the low energy electrons and their measured contribution represents, as expected, about % of the total heat load measured. In the field-free regions, the heat load measured by the pick-up calorimeters decreased by a factor of 2 after 4 days and then remained constant due to the extinction of the electron cloud in the field-free regions. The calculated heat load (strip-detectors) before the scrubbing run and with a single-batch injection was around.4 W/m, and it decreased down to mw/m after days. The estimated heat load with batches injected is mw/m. N electrons (A/m) Field free Ratio to batch Heat load (mw/m) N electrons (A/m) Dipole field Ratio to batch Heat load (mw/m) st scrubbing run (May2), days of LHC-type beams before scrubbing.8e- 9 not measured to "protect" the batch after scrubbing 2.E- 8 strip detector from an expected After the st scrubbing run (May 22) and an air exposure during 4 hours batch.4e- 2.4E batches.8e E N e- batches.e E batches.9e nd scrubbing run (September 22), 4 days of LHC-type beams before 2 nd scrubbing 2.4E-4 42 Batch after 2 nd scrubbing 2.E before 2 nd scrubbing 4.E Batches after 2 nd scrubbing 4.E-. 24 before 2 nd scrubbing 8.E-4 47 Batches after 2 nd scrubbing.e and with the ramp at 4 GeV N e- batch 4.4E- 2 2 batches 9.E- 2.2 batches 4.E batches.2e batches + ramp.e Table : Heat loads calculated from both the electron could intensity (N electrons ) and the electron energy distribution in dipole and field-free regions. In the dipole field regions, the heat load could not be measured at the start up after the shutdown due to the saturation of the acquisition cards. Before the 2 nd scrubbing run and after resetting the strip-detectors by an air exposure, the heat load was measured with 4 batches injected and was around. W/m. This value decreased down to 7 mw/m after 4 days. The ramp to or 4 GeV doubled the electron cloud activity in the dipole field regions and the heat load estimated with the ramp was mw/m. No effect could be measured in the field-free regions with up to 4 batchinjections. Results are summarised in Table. Field-free N electrons Heat load (mw/m) Dipole field N electrons Heat load (mw/m) After scrubbing runs Filling factor or 4 / (SPS).4E- 4.4E E-4 2.2E-4 2 Number of.e E-4 27 batches E ramp - -.E- 92 Filling factor (LHC) No ramp.e- 4 2.E- 84 Ramp at 4 GeV - -.2E- 894 Table 2: Electron cloud activities and calculated heat loads scaled to the LHC filling factor. HP = Half Period (in the SPS ring) 7
9 .2 Scaling to the LHC accelerator Experiments have been made to measure the dependence of the electron cloud activity on the filling factor. At nominal intensity, the calculated heat loads assuming the correction factors in the dipole and fieldfree regions introduced by the different filling factors between the SPS and the LHC, are given in Table 2. The scaling made in Table 2 assumes that the electron cloud build up will increase linearly with the number of batches injected which is thought to be a pessimistic hypothesis mainly due to the space charge limitations. CONCLUSIONS As the LHC injector, the scrubbing runs confirmed that after days of scrubbing, the SPS should be able to inject or 4 batches at nominal intensity into the LHC. However, the electron cloud is still visible with 4 batches injected at nominal intensity in the arcs (dipole field) of the SPS after about hours of LHC-type beams, both as pressure rises and by the electron signals collected by the strip-detectors. In the field-free regions, i.e. in the long straight sections, the electron cloud activity decreased below the detection level of the stripdetectors (< -9 A/m). This observation is not in contradiction with the scrubbing efficiency since most of the LHC beam time used for the scrubbing was with or 2 batches injected with bunch intensities close to the electron cloud threshold after 4 days of scrubbing. As the scrubbing efficiency depends on the amount and energy of the impinging electrons (bunch intensity, bunch length, number of batches) and similarly to RF and HV devices, the scrubbing efficiency is limited by the parameters used during the scrubbing. The scrubbing will not be effective if running conditions are more favourable for the electron cloud build up. The ultimate SEY value reached after 4 days in the field-free regions in the SPS, δ=., shows the multipacting threshold under these conditions, consistent with recent analytical calculations []. The increase of the SEY (δ) observed when the SPS is not operated with LHC-type beams is not an issue since several measurements showed that the SEY recovered its initial value (before drifting) after 4 hours of operation with LHC-type beams above the electron cloud thresholds. The measurements made with a ramp in energy ( or 4 GeV) showed that additional measurements are required to quantify the effect of the bunch length shortening and of the beam orbit displacements expected during the ramp. Preliminary measurements gave an increase by a factor of 2 when shortening the bunch (%) and also a factor of 2 due to the ramp. Therefore, the bunch length variations could explain part of the increase observed during the ramp. For the LHC, a major concern is the excessive heat load due to the electron cloud. Data have been collected and are being compared with the predictions from simulations. A tentative of scaling to the LHC has been made in Table 2, estimations vary between. and.9 W/m in presence or not of a ramp in energy. However, these values must be balanced against the limited amount of beam time with 4 batches injected, an additional decrease ( ) is expected if doing the scrubbing run with 4 batches injected. The LHC situation is also expected to be more complicated since most of the machine is at a cryogenic temperature and therefore the gasses cryosorbed on the inner surfaces of the vacuum chambers could modify the present picture obtained at room temperature. The scrubbing is not yet confirmed on cold surfaces where the efficiency of the impinging electrons could be reduced due to the energy reduction introduced by the gasses cryosorbed on the surfaces. The different filling schemes in the two machines also complicate the extrapolation from the SPS situation to the LHC. In the SPS and with 4 batches injected, the surviving electrons are though to be lost in the 4. µs between the 4 th batch passage and a new passage of the st batch. In the LHC [], the situation could be less favourable since the ring will be full of batches and the maximum spacing between batches will not exceed µs, required by the rise time of the LHC dump kickers. If the electrons from the cloud survive these gaps, the build up may be significantly enhanced. Finally, even if the measurements made in the SPS at room temperature and in the future at cryogenic temperature are difficult to extrapolate to the LHC, these results are important both qualitatively and quantitatively to benchmark the simulations. The latest comparison showed that the simulations are qualitatively in good agreement with the SPS measurements. The appearance of two lateral strips in a dipole field above.x p/bunch and of a rd central strip at higher bunch intensities were predicted and are consistent with the strip-detector measurements. 7 REFERENCES [] J.M. Jimenez and al., Workshop Chamonix XI (2) [2] J.M. Jimenez and al., PAC, CHICAGO (2) [] J.M. Jimenez et al., LHC Project Report 2(2) [4] F. Zimermann and al., Workshop Chamonix X, (2) [] F. Zimmermann and al., Mini-Workshop CERN 22 [] F. Zimmermann, Workshop Chamonix XII (22) [7] N. Kos, EDMS 288 (CERN) [8] N. Hilleret and al, Scrubbing days CERN 22 [9] V. Baglin, Scrubbing days CERN 22 [] L. Vos, CERN (to be published) [] O. Brunning, Minutes of the 9 th PLC9 (CERN) ACKNOWLEDGMENTS K. Cornelis, D. Manglunki, SPS and PS Operators, T. Bohl, P. Baudrenghien, W. Hofle, J. Arnold 2, J-C. Billy 2, G. Mathis 2, J. Ramillon, N. Munda, G. Favre, D. Valero, M. Blanc and the Main Workshop. AB, 2 AT and EST Divisions, CERN. 8
Electron Cloud Studies made at CERN in the SPS
Electron Cloud Studies made at CERN in the SPS J.M. Jimenez On behalf of the Electron Cloud Study Team, a Collaboration between AT and AB Departments Main Topics Introduction LHC Injectors SPS Running
More informationExperimental Results of a LHC Type Cryogenic Vacuum System Subjected to an Electron Cloud
Experimental Results of a LHC Type Cryogenic Vacuum System Subjected to an Electron Cloud V. Baglin, B. Jenninger CERN AT-VAC, Geneva 1. Introduction LHC & Electron Cloud LHC cryogenic vacuum system 2.
More information1.1 Electron-Cloud Effects in the LHC
11 1.1 Electron-Cloud Effects in the LHC F. Zimmermann, E. Benedetto 1 mail to: frank.zimmermann@cern.ch CERN, AB Department, ABP Group 1211 Geneva 23, Switzerland 1.1.1 Introduction The LHC is the first
More informationA SIMULATION STUDY OF THE ELECTRON CLOUD IN THE EXPERIMENTAL REGIONS OF LHC
A SIMULATION STUDY OF THE ELECTRON CLOUD IN THE EXPERIMENTAL REGIONS OF LHC A. Rossi, G. Rumolo and F. Ziermann, CERN, Geneva, Switzerland Abstract The LHC experimental regions (ATLAS, ALICE, CMS and LHC
More information(4) vacuum pressure & gas desorption in the IRs ( A.
Electron Cloud Effects in the LHC Frank Zimmermann,, SL/AP (1) heat load on the beam screen inside the s.c. magnets (4 20 K) (2) heat load on the cold bore (1.9 K) (3) beam instability at injection (4)
More informationLHC operation in 2015 and prospects for the future
LHC operation in 2015 and prospects for the future Moriond Workshop La Thuile March 2016 Jörg Wenninger CERN Beams Department Operation group / LHC For the LHC commissioning and operation teams 1 Moriond
More informationElectron cloud observation in the LHC
Electron cloud observation in the LHC Giovanni Rumolo IPAC 11, San Sebastian (Spain), 8 September 2011 On behalf of the large team of experimenters and simulators G. Arduini, V. Baglin, H. Bartosik, N.
More informationULTIMATE LHC BEAM. G. Arduini, CERN, Geneva, Switzerland
Abstract The present status of the nominal LHC beam in the LHC injector complex and the limitations towards the achievement of the ultimate brightness are outlined. ULTIMATE LHC BEAM G. Arduini, CERN,
More informationElectron Cloud Studies
Electron Cloud Studies Tom Kroyer, Edgar Mahner,, Fritz Caspers, CERN LHC MAC, 7. December 2007 Agenda Introduction to electron cloud effects Overview over possible remedies surface coatings rough surfaces
More informationExperience from the LEP Vacuum System
Experience from the LEP Vacuum System O. Gröbner CERN, LHC-VAC Workshop on an e + e - Ring at VLHC ITT, 9-11 March 2001 3/4/01 O. Gröbner, CERN-LHC/VAC References 1) LEP Design Report, Vol.II, CERN-LEP/84-01,
More informationLHC commissioning. 22nd June Mike Lamont LHC commissioning - CMS 1
LHC commissioning Mike Lamont AB-OP nd June 005.06.05 LHC commissioning - CMS 1 Detailed planning for 7-87 8 and 8-18 005 006 Short Circuit Tests CNGS/TI8/IT1 HWC LSS.L8.06.05 LHC commissioning - CMS Sector
More informationElectron cloud effects for PS2, SPS(+) and LHC
Electron cloud effects for PS2, SPS(+) and LHC G. Rumolo CERN, Geneva, Switzerland Abstract Electron cloud effects are expected to be enhanced and play a central role in limiting the performance of the
More informationLHC Upgrade Plan and Ideas - scenarios & constraints from the machine side
LHC Upgrade Plan and Ideas - scenarios & constraints from the machine side Frank Zimmermann LHCb Upgrade Workshop Edinburgh, 11 January 2007 Frank Zimmermann, LHCb Upgrade Workshop time scale of LHC upgrade
More informationLinear Collider Collaboration Tech Notes
LCC-0124 SLAC-PUB-9814 September 2003 Linear Collider Collaboration Tech Notes Recent Electron Cloud Simulation Results for the NLC and for the TESLA Linear Colliders M. T. F. Pivi, T. O. Raubenheimer
More informationEnergy Spectrum Measurement of the Multipacting Electons in the SPS. Analysis of the Possible Utilisation of the BGIP Monitor
SL-Note-2000-040 BI Energy Spectrum Measurement of the Multipacting Electons in the SPS. Analysis of the Possible Utilisation of the BGIP Monitor Pivi, M. LHC Division VAC Group Variola, A. SL Division
More informationElectron Cloud and Ion Effects. G. Arduini CERN SL Division
Electron Cloud and Ion Effects G. Arduini CERN SL Division Introduction! Understanding and control of impedances has allowed to design machines with higher and higher brilliance.! Since several years now
More informationMagnetic and Electric Field Effects on the Photoelectron Emission from Prototype LHC Beam Screen Material
EUOPEAN OGANIZATION FO NUCLEA ESEACH European Laboratory for Particle Physics Large Hadron Collider Project LHC Project eport 373 Magnetic and Electric Field Effects on the Photoelectron Emission from
More informationOTHER MEANS TO INCREASE THE SPS 25 ns PERFORMANCE TRANSVERSE PLANE
OTHER MEANS TO INCREASE THE SPS 25 ns PERFORMANCE TRANSVERSE PLANE H. Bartosik, G. Arduini, A. Blas, C. Bracco, T. Bohl, K. Cornelis, H. Damerau, S. Gilardoni, S. Hancock, B. Goddard, W. Höfle, G. Iadarola,
More informationElectron-Cloud Theory & Simulations
(1) e cloud build up Electron-Cloud Theory & Simulations Frank Zimmermann,, SL/AP distribution, line & volume density, dose ( scrubbing), energy spectrum, LHC heat load, various fields (dipole, solenoids,
More informationThe LHC: the energy, cooling, and operation. Susmita Jyotishmati
The LHC: the energy, cooling, and operation Susmita Jyotishmati LHC design parameters Nominal LHC parameters Beam injection energy (TeV) 0.45 Beam energy (TeV) 7.0 Number of particles per bunch 1.15
More informationElectron cloud experiments, and cures in RHIC
Electron cloud experiments, and cures in RHIC Wolfram Fischer M. Blaskiewicz, H.-C. Hseuh, H. Huang, U. Iriso, V. Ptitsyn, T. Roser, P. Thieberger, D. Trbojevic, J. Wei, S.Y. Zhang PAC 07 Albuquerque,
More informationStudy of Distributed Ion-Pumps in CESR 1
Study of Distributed Ion-Pumps in CESR 1 Yulin Li, Roberto Kersevan, Nariman Mistry Laboratory of Nuclear Studies, Cornell University Ithaca, NY 153-001 Abstract It is desirable to reduce anode voltage
More informationStatus and Outlook of the LHC
Status and Outlook of the LHC Enrico Bravin - CERN BE-BI J-PARC visit seminar 6 July 2017 Outlook Overview of LHC Objectives for run2 Parameters for 2016/2017 and differences w.r.t. 2015 Summary of commissioning
More informationEXPERIMENTAL INVESTIGATIONS OF THE ELECTRON CLOUD KEY PARAMETERS
EXPERIMENTAL INVESTIGATIONS OF THE ELECTRON CLOUD KEY PARAMETERS V. Baglin, I.R. Collins, J. Gómez-Goñi *, O. Gröbner, B. Henrist, N. Hilleret, J M. Laurent, M. Pivi, CERN, Geneva, Switzerland R. Cimino,
More informationBeam-induced heat loads on the beam screens of the inner triplets for the HL-LHC
CERN-ACC-2018-0009 Galina.Skripka@cern.ch Beam-induced heat loads on the beam screens of the inner triplets for the HL-LHC G. Skripka and G. Iadarola CERN, Geneva, Switzerland Keywords: LHC, HL-LHC, heat
More informationRaising intensity of the LHC beam in the SPS - longitudinal plane
SL-Note-- MD Raising intensity of the LHC beam in the SPS - longitudinal plane Ph. Baudrenghien, T. Bohl, T. Linnecar, E. Shaposhnikova Abstract Different aspects of the LHC type beam capture and acceleration
More informationLuminosity for the 100 TeV collider
Luminosity for the 100 TeV collider M.L.Mangano, contribution to the Luminosity discussion session, Jan 15 2015 IAS programme on The Future of High Energy Physics Critical parameter to determine the physics
More informationSimulations and Measurements of Secondary Electron Emission Beam Loss Monitors for LHC
Simulations and Measurements of Secondary Electron Emission Beam Loss Monitors for LHC Daniel Kramer,, Eva Barbara Holzer,, Bernd Dehning, Gianfranco Ferioli, Markus Stockner CERN AB-BI BI 4.10.2006 IPRD06,
More informationATLAS New Small Wheel Phase I Upgrade: Detector and Electronics Performance Analysis
ATLAS New Small Wheel Phase I Upgrade: Detector and Electronics Performance Analysis Dominique Trischuk, Alain Bellerive and George Iakovidis IPP CERN Summer Student Supervisor August 216 Abstract The
More informationGianluigi Arduini CERN - Beams Dept. - Accelerator & Beam Physics Group
Gianluigi Arduini CERN - Beams Dept. - Accelerator & Beam Physics Group Acknowledgements: O. Brüning, S. Fartoukh, M. Giovannozzi, G. Iadarola, M. Lamont, E. Métral, N. Mounet, G. Papotti, T. Pieloni,
More informationBeam losses versus BLM locations at the LHC
Geneva, 12 April 25 LHC Machine Protection Review Beam losses versus BLM locations at the LHC R. Assmann, S. Redaelli, G. Robert-Demolaize AB - ABP Acknowledgements: B. Dehning Motivation - Are the proposed
More informationLarge Hadron Collider at CERN
Large Hadron Collider at CERN Steve Playfer 27km circumference depth 70-140m University of Edinburgh 15th Novemebr 2008 17.03.2010 Status of the LHC - Steve Playfer 1 17.03.2010 Status of the LHC - Steve
More informationBEAM SCREEN ISSUES (with 20 T dipole magnets instead of 8.3 T)
BEAM SCREEN ISSUES (with 20 T dipole magnets instead of 8.3 T) Introduction and current LHC beam screen Magneto-Resistance (MR) What was done in the past (approx. of the approx. Kohler s rule) Exact and
More informationHL-LHC OPERATIONAL SCENARIOS
CERN-ACC-NOTE-2015-0009 2015-05-19 Elias.Metral@cern.ch HL-LHC OPERATIONAL SCENARIOS G. Arduini, N. Biancacci, O. Brüning, R. De Maria, M. Giovannozzi, W. Höfle, K. Li, E. Métral, J.E. Muller, Y. Papaphilippou,
More informationOptimization of the SIS100 Lattice and a Dedicated Collimation System for Ionisation Losses
Optimization of the SIS100 Lattice and a Dedicated Collimation System for Ionisation Losses P. Spiller, K. Blasche, B. Franczak, J. Stadlmann, and C. Omet GSI Darmstadt, D-64291 Darmstadt, Germany Abstract:
More informationLawrence Berkeley National Laboratory Lawrence Berkeley National Laboratory
Lawrence Berkeley National Laboratory Lawrence Berkeley National Laboratory Title ECLOUD in PS, PS+, SPS+: AN UPDATE Permalink https://escholarship.org/uc/item/7rf0rz Author Furman, M.A. Publication Date
More informationChamonix XII: LHC Performance Workshop. Requirements from the experiments in Year 1*
Chamonix XII: LHC Performance Workshop Requirements from the experiments in Year 1* 3-8 March, 2003 Experiments: Foreseen Status in April 2007 Physics Reach in the First Year Requirements from the Experiments
More informationELECTRON COOLING OF PB54+ IONS IN LEIR
ELECTRON COOLING OF PB+ IONS IN LEIR G. Tranquille, CERN, Geneva, Switzerland Abstract Electron cooling is central in the preparation of dense bunches of lead beams for the LHC. Ion beam pulses from the
More informationLongitudinal Dynamics
Longitudinal Dynamics F = e (E + v x B) CAS Bruges 16-25 June 2009 Beam Dynamics D. Brandt 1 Acceleration The accelerator has to provide kinetic energy to the charged particles, i.e. increase the momentum
More informationVacuum System of Synchrotron radiation sources
3 rd ILSF Advanced School on Synchrotron Radiation and Its Applications September 14-16, 2013 Vacuum System of Synchrotron radiation sources Prepared by: Omid Seify, Vacuum group, ILSF project Institute
More informationPlans for 2016 and Run 2
Plans for 2016 and Run 2 Mike Lamont An attempt at synthesis Acknowledgements all round After LS1 It s going to be like after a war Serge Claudet Evian 2012 Where are we? 1/2 6.5 TeV, 2*80 cm, 2*levelled
More informationBeam heat load due to geometrical and resistive wall impedance in COLDDIAG
Beam heat load due to geometrical and resistive wall impedance in COLDDIAG Sara Casalbuoni, Mauro Migliorati, Andrea Mostacci, Luigi Palumbo, Bruno Spataro 2012 JINST 7 P11008, http://iopscience.iop.org/17480221/7/11/p11008
More informationOPERATIONAL BEAMS FOR THE LHC
OPERATIONAL BEAMS FOR THE LHC Y. Papaphilippou, H. Bartosik, G. Rumolo, D. Manglunki, CERN, Geneva, Switzerland Abstract The variety of beams, needed to set-up in the injectors as requested in the LHC,
More informationRF BARRIER CAVITY OPTION FOR THE SNS RING BEAM POWER UPGRADE
RF BARRIER CAVITY OPTION FOR THE SNS RING BEAM POWER UPGRADE J.A. Holmes, S.M. Cousineau, V.V. Danilov, and A.P. Shishlo, SNS, ORNL, Oak Ridge, TN 37830, USA Abstract RF barrier cavities present an attractive
More informationANSWERS TO NICOLAAS KOS FOR HIS PAPER Cold Beam Vacuum System for the LHC IR Upgrade Phase-1
ANSWERS TO NICOLAAS KOS FOR HIS PAPER Cold Beam Vacuum System for the LHC IR Upgrade Phase-1 Maximum acceptable width for the pumping slots for a new beam screen wall thickness of 1.5 mm (SS only, and
More informationMaps, electron-clouds in RHIC and first-order phase-transitions
C-A/AP/#197 April 005 Maps, electron-clouds in RHIC and first-order phase-transitions P. Thieberger, U. Iriso and S. Peggs Collider-Accelerator Department Brookhaven National Laboratory Upton, NY 11973
More informationBeam induced heat loads on the beam-screens of the twin-bore magnets in the IRs of the HL-LHC
CERN-ACC-2016-0112 Giovanni.Iadarola@cern.ch Beam induced heat loads on the beam-screens of the twin-bore magnets in the IRs of the HL-LHC G. Iadarola, E. Metral, G. Rumolo CERN, Geneva, Switzerland Abstract
More informationDetailed Characterization of Vacuum Chamber Surface Properties Using Measurements of the Time Dependence of Electron Cloud Development
45th ICFA Beam Dynamic Workshop June 8 12, 2009, Cornell University, Ithaca New York Detailed Characterization of Vacuum Chamber Surface Properties Using Measurements of the Time Dependence of Electron
More informationRadiation damage in diamond sensors at the CMS experiment of the LHC
Radiation damage in diamond sensors at the CMS experiment of the LHC Moritz Guthoff on behalf of the CMS beam monitoring group ADAMAS Workshop 2012, GSI, Germany IEKP-KIT / CERN KIT University of the State
More informationSMOG: an internal gas target in LHCb?
System for Measuring the Overlap with Gas SMOG: an internal gas target in LHCb? intro: LHCb/VELO luminosity calibration what we use the SMOG for hardware implementation operational aspects impact on LHC
More informationPlans for ions in the injector complex D.Manglunki with the help of I-LHC and LIU-PT teams
Plans for ions in the injector complex D.Manglunki with the help of I-LHC and LIU-PT teams Special acknowledgements to T.Bohl, C.Carli, E.Carlier, H.Damerau, L.Ducimetière, R.Garoby, S.Gilardoni, S.Hancock,
More informationRF System Calibration Using Beam Orbits at LEP
EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH CERN SL DIVISION CERN-SL-22-28 OP LEP Energy Working Group 2/1 RF System Calibration Using Beam Orbits at LEP J. Wenninger Abstract The target for beam energy
More informationBeam Diagnostics. Measuring Complex Accelerator Parameters Uli Raich CERN BE-BI
Beam Diagnostics Measuring Complex Accelerator Parameters Uli Raich CERN BE-BI CERN Accelerator School Prague, 2014 Contents Some examples of measurements done with the instruments explained during the
More informationChallenges and Plans for the Proton Injectors *
Chapter 16 Challenges and Plans for the Proton Injectors * R. Garoby CERN, BE Department, Genève 23, CH-12, Switzerland The flexibility of the LHC injectors combined with multiple longitudinal beam gymnastics
More informationLHC accelerator status and prospects. Frédérick Bordry Higgs Hunting nd September Paris
LHC accelerator status and prospects 2 nd September 2016 - Paris LHC (Large Hadron Collider) 14 TeV proton-proton accelerator-collider built in the LEP tunnel Lead-Lead (Lead-proton) collisions 1983 :
More informationFIG. 5: Voltage scan in TiN coated chicane chamber: 1x45x1.25mA e+, 5.3GeV, 14ns.
APS/-QED Studies of Electron Cloud Growth and Mitigation in Dipole and Quadrupole Fields Using Retarding Field Analyzers J.R. Calvey, M.G. Billing, J.V. Conway, G. Dugan, S. Greenwald, Y. Li, X. Liu, J.A.
More informationThe MD was done at 450GeV using beam 2 only. An MD focussing on injection of bunches with nominal emittance was done in parallel on beam 1.
CERN-ATS-Note-2011-065 MD 2011-08-08 Tobias.Baer@cern.ch MKI UFOs at Injection Tobias BAER, Mike BARNES, Wolfgang BARTMANN, Chiara BRACCO, Etienne CARLIER, Christophe CHANAVAT, Lene Norderhaug DROSDAL,
More informationResults of UFO dynamics studies with beam in the LHC
Journal of Physics: Conference Series PAPER OPEN ACCESS Results of UFO dynamics studies with beam in the LHC To cite this article: B Lindstrom et al 2018 J. Phys.: Conf. Ser. 1067 022001 View the article
More informationImportance of realistic surface related properties as input to e-cloud simulations.
Importance of realistic surface related properties as input to e-cloud simulations. R. Cimino LNF Frascati (Italy) The problem of input parameters: a detailed analysis by a test case (the cold arcs of
More informationHL LHC: impedance considerations for the new triplet layout in IR1 & 5
HL LHC: impedance considerations for the new triplet layout in IR1 & 5 N. Mounet, A. Mostacci, B. Salvant, C. Zannini and E. Métral Acknowledgements: G. Arduini, C. Boccard, G. Bregliozzi, L. Esposito,
More informationFrequency and time domain analysis of trapped modes in the CERN Proton Synchrotron
Frequency and time domain analysis of trapped modes in the CERN Proton Synchrotron Serena Persichelli CERN Impedance and collective effects BE-ABP-ICE Abstract The term trapped mode refers to a resonance
More informationPractical Lattice Design
Practical Lattice Design Dario Pellegrini (CERN) dario.pellegrini@cern.ch USPAS January, 15-19, 2018 1/17 D. Pellegrini - Practical Lattice Design Lecture 5. Low Beta Insertions 2/17 D. Pellegrini - Practical
More informationphotoemission, secondary emission, magnetic
Electron-Cloud Simulations: Build Up and Related Effects Frank Zimmermann, G. Rumolo,, SL/AP (1) Simulation model photoemission, secondary emission, magnetic fields, beam fields, image charges, space charge
More informationA Luminosity Leveling Method for LHC Luminosity Upgrade using an Early Separation Scheme
LHC Project Note 03 May 007 guido.sterbini@cern.ch A Luminosity Leveling Method for LHC Luminosity Upgrade using an Early Separation Scheme G. Sterbini and J.-P. Koutchouk, CERN Keywords: LHC Luminosity
More informationLHC Luminosity and Energy Upgrade
LHC Luminosity and Energy Upgrade Walter Scandale CERN Accelerator Technology department EPAC 06 27 June 2006 We acknowledge the support of the European Community-Research Infrastructure Activity under
More informationStatus and Results of the UA9 Crystal Collimation Experiment at the CERN-SPS
HB2012 - Beijing - 18 September 2012 Status and Results of the UA9 Crystal Collimation Experiment at the CERN-SPS Simone Montesano (CERN) for the UA9 collaboration Silicon strip crystal Outline Crystal
More informationBeam. RF antenna. RF cable
Status of LEP2 J. Wenninger, SL Operation for the SL division LEPC September 1998 Outline Optics and RF for 1998 Beam current limitations Injection and ramp Performance at high energy Conclusions LEPC/15-09-98
More informationResults on a-c tubes subjected to synchrotron irradiation
Results on a-c tubes subjected to synchrotron irradiation V. Baglin, P. Chiggiato, P. Costa-Pinto, B. Henrist (CERN, Geneva) V. Anashin, D. Dorokhov. A. Semenov, A. Krasnov, D. Shwartz, A. Senchenko (,
More information(a) (b) Fig. 1 - The LEP/LHC tunnel map and (b) the CERN accelerator system.
Introduction One of the main events in the field of particle physics at the beginning of the next century will be the construction of the Large Hadron Collider (LHC). This machine will be installed into
More informationTobias Baer February, 9 th 2012
UFOs Will they take over? Chamonix Workshop 2012 Tobias Baer February, 9 th 2012 Acknowledgements: W. Bartmann, M. Barnes, C. Bracco, F. Cerutti, B. Dehning, L. Ducimetière, A. Ferrari, N. Fuster Martinez,
More informationStudies of trapped modes in the new extraction septum of the CERN Proton Synchrotron
Studies of trapped modes in the new extraction septum of the CERN Proton Synchrotron Serena Persichelli CERN Impedance and collective effects (BE-ABP-ICE) LIU LHC Injectors Upgrade project Università di
More informationSupercritical Helium Cooling of the LHC Beam Screens
EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH European Laboratory for Particle Physics Large Hadron Collider Project LHC Project Report Supercritical Helium Cooling of the LHC Beam Screens Emmanuel Hatchadourian,,
More informationElectron Cloud Studies for KEKB and ATF KEK, May 17 May 30, 2003
Electron Cloud Studies for KEKB and ATF KEK, May 17 May 3, 23 F. Zimmermann April 12, 23 Abstract I describe a few recent electron-cloud simulations for KEKB and the ATF. For KEKB the dependence of the
More informationDYNAMIC APERTURE STUDIES FOR HL-LHC V1.0 *
SLAC PUB 17366 December 2018 DYNAMIC APERTURE STUDIES FOR HL-LHC V1.0 * Y. Cai, R. De Maria, M. Giovannozzi, Y. Nosochkov, F.F. Van der Veken ;1 CERN, CH-1211 Geneva 23, Switzerland SLAC National Accelerator
More informationLHC Run 2: Results and Challenges. Roderik Bruce on behalf of the CERN teams
LHC Run 2: Results and Challenges Roderik Bruce on behalf of the CERN teams Acknowledgements A big thanks to all colleagues involved across various teams! Special thanks for material and discussions G.
More informationPolycrystalline CdTe Detectors: A Luminosity Monitor for the LHC
EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH CERN AB DIVISION CERN-AB-2003-003 BDI Polycrystalline CdTe Detectors: A Luminosity Monitor for the LHC E. Gschwendtner; M. Placidi; H. Schmickler Abstract The
More informationBeam Diagnostics Lecture 3. Measuring Complex Accelerator Parameters Uli Raich CERN AB-BI
Beam Diagnostics Lecture 3 Measuring Complex Accelerator Parameters Uli Raich CERN AB-BI Contents of lecture 3 Some examples of measurements done with the instruments explained during the last 2 lectures
More informationThe CMS ECAL Laser Monitoring System
The CMS ECAL Laser Monitoring System Adolf Bornheim California Institute of Technology, 1200 East California Blvd., Pasadena, CA 91125, USA Abstract. The CMS detector at LHC will be equipped with a high
More informationShort Introduction to CLIC and CTF3, Technologies for Future Linear Colliders
Short Introduction to CLIC and CTF3, Technologies for Future Linear Colliders Explanation of the Basic Principles and Goals Visit to the CTF3 Installation Roger Ruber Collider History p p hadron collider
More informationDevelopment of Long Pulse Neutral Beam Injector on JT-60U for JT-60SA
Development of Long Pulse Neutral Beam Injector on JT-60U for JT-60SA M.Hanada, Y.Ikeda, L. Grisham 1, S. Kobayashi 2, and NBI Gr. Japan Atomic Energy Agency, 801-1 Mukohyama, Naka, Ibaraki-ken, 311-0193,
More informationPREPARING THE SPS COMPLEX ALIGNMENT FOR FUTURE LHC RUNS
PREPARING THE SPS COMPLEX ALIGNMENT FOR FUTURE LHC RUNS P. Bestmann, P. Dewitte, CERN, Geneva, Switzerland Abstract The Super Proton Synchrotron (SPS) is the last machine in the LHC injector chain. Operational
More informationPreliminary design of the new HL-LHC beam screen for the low-β triplets
Preliminary design of the new HL-LHC beam screen for the low-β triplets Marco Morrone TE-VSC-DLM 15/10/2015 Contents o CERN The Hi Lumi upgrade o Functional requirements -Functional study -Current vs new
More informationCMS Note Mailing address: CMS CERN, CH-1211 GENEVA 23, Switzerland
Available on CMS information server CMS NOTE 1996/005 The Compact Muon Solenoid Experiment CMS Note Mailing address: CMS CERN, CH-1211 GENEVA 23, Switzerland Performance of the Silicon Detectors for the
More informationBEAM TESTS OF THE LHC TRANSVERSE FEEDBACK SYSTEM
JINR BEAM TESTS OF THE LHC TRANSVERSE FEEDBACK SYSTEM W.Höfle, G.Kotzian, E.Montesinos, M.Schokker, D.Valuch (CERN) V.M. Zhabitsky (JINR) XXII Russian Particle Accelerator Conference 27.9-1.1. 21, Protvino
More informationSLS at the Paul Scherrer Institute (PSI), Villigen, Switzerland
SLS at the Paul Scherrer Institute (PSI), Villigen, Switzerland Michael Böge 1 SLS Team at PSI Michael Böge 2 Layout of the SLS Linac, Transferlines Booster Storage Ring (SR) Beamlines and Insertion Devices
More informationTRANSVERSE DAMPER. W. Höfle, CERN, Geneva, Switzerland. Abstract INTRODUCTION AND HIGHLIGHTS IN Controlled Transverse Blow-up
TRANSVERSE DAMPER W. Höfle, CERN, Geneva, Switzerland Abstract Plans for the operation of the transverse damper in 2012 at bunch spacings of 50 ns and 25 ns and at increased collision energy will be reviewed.
More informationCompressor Lattice Design for SPL Beam
EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH CERN A&B DIVISION AB-Note-27-34 BI CERN-NUFACT-Note-153 Compressor Lattice Design for SPL Beam M. Aiba Abstract A compressor ring providing very short proton
More informationTheory English (Official)
Q3-1 Large Hadron Collider (10 points) Please read the general instructions in the separate envelope before you start this problem. In this task, the physics of the particle accelerator LHC (Large Hadron
More informationLawrence Berkeley National Laboratory Lawrence Berkeley National Laboratory
Lawrence Berkeley National Laboratory Lawrence Berkeley National Laboratory Title Electron-Cloud Build-up in the FNAL Main Injector Permalink https://escholarship.org/uc/item/4v35z0wd Author Furman, M.A.
More informationElectron Cloud Issues for the Advanced Photon Source Superconducting Undulator
Electron Cloud Issues for the Advanced Photon Source Superconducting Undulator Katherine Harkay Electron Cloud Workshop, Cornell, Oct. 8-12, 2010 Acknowledgements: Yury Ivanyushenkov, Robert Kustom, Elizabeth
More informationLHC Collimation and Loss Locations
BLM Audit p. 1/22 LHC Collimation and Loss Locations BLM Audit Th. Weiler, R. Assmann, C. Bracco, V. Previtali, S Redaelli Accelerator and Beam Department, CERN BLM Audit p. 2/22 Outline Introduction /
More informationThe TESLA Dogbone Damping Ring
The TESLA Dogbone Damping Ring Winfried Decking for the TESLA Collaboration April 6 th 2004 Outline The Dogbone Issues: Kicker Design Dynamic Aperture Emittance Dilution due to Stray-Fields Collective
More informationElectron cloud buildup and instability: Numerical simulations for the CERN Proton Synchrotron
PHYSICAL REVIEW SPECIAL TOPICS - ACCELERATORS AND BEAMS, VOLUME 6, (23) Electron cloud buildup and instability: Numerical simulations for the CERN Proton Synchrotron M. Giovannozzi, E. Métral, G. Métral,
More informationThe Large Hadron Collider Lyndon Evans CERN
The Large Hadron Collider Lyndon Evans CERN 1.9 K 2.728 K T The coldest ring in the universe! L.R. Evans 1 The Large Hadron Collider This lecture. LHC Technologies Magnets Cryogenics Radiofrequency Vacuum
More informationTUNE SPREAD STUDIES AT INJECTION ENERGIES FOR THE CERN PROTON SYNCHROTRON BOOSTER
TUNE SPREAD STUDIES AT INJECTION ENERGIES FOR THE CERN PROTON SYNCHROTRON BOOSTER B. Mikulec, A. Findlay, V. Raginel, G. Rumolo, G. Sterbini, CERN, Geneva, Switzerland Abstract In the near future, a new
More informationCommissioning of the LHC collimation system S. Redaelli, R. Assmann, C. Bracco, M. Jonker and G. Robert-Demolaize CERN, AB department
39 th ICFA Advance Beam dynamics Workshop High Intensity High Brightness Hadron Beams - HB 2006 Tsukuba, May 29 th - June 2 nd, 2006 Commissioning of the LHC collimation system S. Redaelli, R. Assmann,
More informationParticles and Universe: Particle accelerators
Particles and Universe: Particle accelerators Maria Krawczyk, Aleksander Filip Żarnecki March 24, 2015 M.Krawczyk, A.F.Żarnecki Particles and Universe 4 March 24, 2015 1 / 37 Lecture 4 1 Introduction 2
More informationThe achievements of the CERN proton antiproton collider
The achievements of the CERN proton antiproton collider Luigi DiLella Scuola Normale Superiore, Pisa, Italy Motivation of the project The proton antiproton collider UA1 and UA2 detectors Discovery of the
More informationElectron cloud detection and characterization in the CERN Proton Synchrotron
PHYSICAL REVIEW SPECIAL TOPICS - ACCELERATORS AND BEAMS 11, 9441 (28) Electron cloud detection and characterization in the CERN Proton Synchrotron Edgar Mahner, Tom Kroyer, and Fritz Caspers CERN, 1211
More informationThanks to all Contributors
Thanks to all Contributors High Gradient versus High Field Dr. José Miguel Jiménez CERN Technology Department Head CERN-Spain Liaison Officer 2 Main topics A worldwide success? Full exploitation of the
More information