Chamonix XII: LHC Performance Workshop. Requirements from the experiments in Year 1*

Transcription

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 Conclusions * On behalf of LHC experiments Gratefully acknowledge help from experiments and machine people Tejinder S. Virdee CERN/Imperial T. Virdee, Chamonix XII, Mar03 1

2 LHCb Plan to be fully installed by Apr 2007 No shutdown needed in 2007 Physics <0.2> pileup events/crossing, i.e cm -2 s 25ns bunch spacing 11.2m away from centre Change magnet polarity from fill-to-fill β* 1 50m T. Virdee, Chamonix XII, Mar03 2

3 HMPID ALICE Plan to be installed (except parts of PHOS,TRD) by Apr 2007 No shutdown needed in 2007 pp running at L cm -2 s -1 TOF TRD TPC t D (TPC) 100 µs β* 10-50m PMD PHOS ITS Muon arm T. Virdee, Chamonix XII, Mar03 3

4 Compact Muon Solenoid Plan to be installed by Apr 2007 [without final pixels in pilot run] except for staged parts: 3 rd forward pixels disks ME4 RPCs in η > 1.6 Desire 2-3 mo. shutdown in 2007 after pilot run To install pixels and fix problems picked up in pilot run At physics startup: # of pileup evts/crossing 2 50% DAQ T. Virdee, Chamonix XII, Mar03 4

5 ATLAS Plan to be installed by Apr 2007 except for staged parts (needed for Hi L): tracker 1 pixel layer, outermost TRT wheels muons: EES & EEL MDTs, half of CSCs LAr: part of ROD system, tile gap scint. forward shielding Shutdown in 07 not in base plan but if done T 3mo. At physics startup: # of pileup evts/crossing % DAQ T. Virdee, Chamonix XII, Mar03 5

6 TOTEM 1 st Run One effective fill a few cm -2 s -1, zero crossing angle, β* =1100m 46 bunches (or even a higher number is desirable) 2 nd Run A few cm -2 s -1, crossing angle, β* =28m T. Virdee, Chamonix XII, Mar03 6

7 Status of April 2007 Installed detectors should have been commissioned (also using cosmics) i.e. Magnets can be powered (to nominal current) Cables (signal, LV, HV etc) go to the right places Pipes (cooling and gas) go to the right places Hardwired Detector Safety Systems operational Detector Control Systems operational Sub-detectors can be powered on Cooling, gas distribution and ventilation systems work Subdetector and overall DAQ systems operational Preliminary calibration (electronic, from construction database ) Some initial (without beam) synchronization has been established T. Virdee, Chamonix XII, Mar03 7

8 Search for the LHC Startup Some numbers At L 0 =10 33 cm -2 s -1 : 1 day 25 pb -1 1 month 0.7 fb -1 Example Discovery Reach (5σ): ATLAS +CMS 10fb -1 per expt. At L 0 = cm -2 s -1 : 1 day 75 pb -1 1 month 2 fb -1 Assumptions 14hr run and 10hr to refill i.e. 1 fill/day τ L 20 hr Efficiency of 2/3 ATLAS +CMS 115 GeV 3 months (80 L 0 =10 33 cm -2 s -1 B-physics potential exploited from the beginning T. Virdee, Chamonix XII, Mar03 8

9 Discovering LHC Startup Will find SUSY quickly if it is there miss CMS q, g mass reach in E + jets inclusive channel T for various integrated luminosities CMS g(3000) miss E T (100 fb -1 ) L dt = 1, 10, 100, 300 fb -1 A 0 = 0, tanβ= 35, µ > 0 miss E T (300 fb -1 ) h(123) Events / 2GeV/c SUSY + SM E miss > 100 GeV/c T P T l(1,2) > 15 GeV tgβ = 2, A 0 = 0, µ<0 m 0 = 200 GeV m 1/2 = 160 GeV SM CMS L int = 1 fb M(l + l ) (GeV/c 2 ) miss E T (10 fb -1 ) miss E T (1 fb -1 ) T. Virdee, Chamonix XII, Mar03 9 m 1/2 (GeV) one TH q(500) h(110) EX Ωh 2 = 0.15 Ωh 2 = 0.4 g(500) 500 Ωh 2 = 1 q(1000) q(2000) q(1500) g(1500) g(2000) g(1000) g(2500) q(2500) Fermilab reach: < 500 GeV m 0 (GeV) one one one cosmologically plausible region DD_2101

10 Physics Impact of Lower Startup For safer and more reliable operation at startup the machine may run at a lower energy ( > 0.9 x nominal) and for at most a few months(higgs will be out of reach during this period). SUSY processes have strong interaction cross-sections lower energy acceptable. We must start running asap. And move to nominal energy asap m H = 130 GeV σ.br 40 fb σ SUSY 150 pb! T. Virdee, Chamonix XII, Mar03 10

11 CMS: H! ZZ! 2e 2µ At nominal proton intensity/bunch (1.1x10 11 p) and nominal β* we get 20 pileup events/crossing superposed on the one of interest For initial physics data taking ATLAS and CMS wish to operate in conditions with < 2 pileup events/crossing Single event Only tracks with p T > 2 GeV are shown NB: Nominal bunch-bunch: 100 W!lν /hr, T. Virdee, Chamonix XII, Mar03 11

12 CMS: H! ZZ! 2e 2µ + 2 pileup events i.e and 25ns bunch spacing + 20 pileup events i.e and 25ns bunch spacing T. Virdee, Chamonix XII, Mar03 12

13 Requirements from Experiments I ATLAS Shutdown after the pilot run not in current plan but wish to retain possibility of requesting it (length 3 mo.) CMS Request shutdown of 2.5 mo. after the pilot run ATLAS & CMS: Prefer data-taking at cm -2 s -1 at 25 ns bunch spacing LHCb The single-beam phase should be with clockwise beam (seen from above) Request collisions also during 43 on 43 bunch operation (a few per turn) Prefer operation at 1-2x10 32 cm -2 s -1 at 25 ns bunch spacing (maximize events with 1 interaction) Sector Test: Wish for small to no impact on their installation after the test. Varying β* ( as well as during a fill!) ALICE pp running at L = cm -2 s -1 (cleanest data for 10 29, no pileup in TPC) Studies of varying β* and displacement of beams (beam halo beam halo) A few good days of Pb-Pb running before a long (> 5 mo.) shutdown T. Virdee, Chamonix XII, Mar03 13

14 Requirements from Experiments II Startup is 4 years away should retain as much flexibility as possible Some short-time access during pilot run At the end of pilot run: hope machine can be stably operated at 25 ns spacing (in addition to 75ns) Change energy only once if a lower energy is chosen for initial running stability during physics data taking important. Wish spectrometer magnets ON during injection to start data-taking asap. Satellite bunch intensity 1% of nominal appears to be acceptable. Duration and pattern of accesses Data Exchange From Expts: Beam condition monitors and other detectors such as: for CMS (HF, ME for halo muons) etc. Relative bunch-bunch luminosity From Machine beam condition, background conditions (vacuum quality etc.) settings of expt-critical collimators, bunch intensities, etc. We (and CERN for power ) should prepare for the possibility of running in winter of 2007 T. Virdee, Chamonix XII, Mar03 14

15 Strawman Timeline and Experiment Activities I 1 st Beam to 1 st Collisions (Pilot Run) Single Beam: April and May Machine: Set-up the machine for safe operation One low intensity bunch! multiple bunches at close to nominal intensity (20 pileup events/crossing!!) Experiments: Synchronization, beam-gas studies and rejection, vacuum quality, profile of beam-gas interactions, muon halo triggers, catalog detector problems Colliding Beams (June) Machine: One bunch on one bunch! 43 x 43 at close to nominal bunch intensity with zero crossing angle! carefully squeeze beams Experiments: Synchronization, record first pp collisions! Catalog detector problems Colliding Beams (July) Machine: Introduce crossing angle and larger no. of bunches 75 ns, 940 bunches at few x cm -2 s ns, 2520 bunches at few x cm -2 s -1, Scrubbing to address electron cloud issues? Experiments: Synchronization, set-up for physics running, pilot physics T. Virdee, Chamonix XII, Mar03 15

16 Shutdown ( 3 mo.) Strawman Timeline and Experiment Activities II 1 st Collisions to cm -2 s -1 (Physics Run starting November) First few weeks: Start with 75 ns, 940 bunches, L = cm -2 s -1 (synchronisation) Increase bunch intensities. When pileup becomes > 2 evts/crossing move to 25ns, 2520 bunches When experiments have understood detector operation at >2 pileup events/crossing possible options are: If 25ns operation is OK, raise L to cm -2 s -1 and integrate physics If and only if 25ns operation shows problems or experiments desire higher integrated luminosity, then run at 75 ns with >2 pileup evts/crossing. Run for 7 mo. (integrating 10fb -1 per ATLAS/CMS) ALICE requests a 2-week Pb-Pb run just before first long shutdown (Alternative: no shutdown! physics run for few months! long winter shutdown) T. Virdee, Chamonix XII, Mar03 16

17 Conclusions The four LHC detectors (with some elements staged) will be ready for first beam in April 2007 Exciting physics is likely to start tumbling out right at the start and at the envisaged initial luminosities! Startup is 4 years away must retain as much flexibility as possible in running scenarios The goal should be to go as fast as possible to stable operation at 25 ns bunch cm -2 s nominal energy Initial physics running should be with < 2 pileup events/crossing. A somewhat lower energy for the initial few months would be acceptable. The exact choice for integrating a high luminosity in the first year can probably be made only in light of experience gained in initial phase. We (and CERN for power.) should prepare for the possibility of running during the winter of T. Virdee, Chamonix XII, Mar03 17