LHCf Technical Design Report. Measurement of Photons and Neutral Pions in the Very Forward Region of LHC

Transcription

1 LHCf Technical Design Report CERN-LHCC LHCF-TDR February 2006 Measurement of Photons and Neutral Pions in the Very Forward Region of LHC O. Adriani(1), L. Bonechi(1), M. Bongi(1), R. D Alessandro(1), D.A. Faus(2), M. Haguenauer(3), Y. Itow (4), K. Kasahara(5), K. Masuda(4), Y. Matsubara(4), H. Menjo(4), Y. Muraki(4), P. Papini(1), T. Sako(4), T. Tamura(6), S. Torii(7), A. Tricomi(8), W.C. Turner(9), J. Velasco(2), K. Yoshida(6) The LHCf collaboration (1) INFN Firenze, Univ. di Firenze, Firenze, Italy (2) IFIC, Centro Mixto CSIC-UVEG, Valencia, Spain (3) Ecole-Polytechnique, Paris, France (4) STE laboratory, Nagoya University, Nagoya, Japan (5) Shibaura Institute of Technology, Saitama, Japan (6) Kanagawa University, Yokohama, Japan (7) RISE, Waseda Univ., Tokyo, Japan (8) INFN Catania, Univ. di Catania, Catania, Italy (9) LBNL, Berkeley, California, USA

2 Highlight of the talk 1. Short history 2. Review of physics 3. Detector overview and background study (after November 16 th LHCC) 4. Progress report on cabling, safety, installation, trigger, luminosity measurement, etc 5. Possible running scenario 6. Summary Many important technical aspects can not be covered in this presentation TDR for details

3 Letter Of Intent: May 2004 Technical report: September 2005 Technical Design Report: February 2006 LHCC October 2005 comments: The physics goals are worthwhile and the proposed experiment appears suited to achieve them A few key issues require immediate consideration, and documentation in the update of the TP: establish official contact with the relevant structures in the AT/AB departments, as well as in ATLAS etc appoint a technical coordinator (possibly located at CERN?) consider and document safety issues On the other hand: the TP is not sufficiently detailed and fails to provide a solid and compelling evidence that the above expectations are justified TDR was released to answer to these questions

4 Main problems in High Energy Cosmic Rays (E>10 15 ev) 1. Composition X max (g/cm 2 ) 2. Spectrum / GZK Cutoff Energy (ev)

5 Development of atmospheric showers Simulation of an atmospheric shower due to a ev proton. The dominant contribution to the energy flux is in the very forward region (θ 0) In this forward region the highest energy available measurements of π 0 cross section were done by UA7 (E=10 14 ev, y = 5 7) The direct measurement of the π production cross section as function of p T is essential to correctly estimate the energy of the primary cosmic rays (LHC: ev)

6 Experimental Method: 2 independent detectors on both sides of IP Detector I Tungsten Scintillator Scintillating fibers INTERACTION POINT Detector II Tungsten Scintillator Silicon µstrips 140 m 140 m Beam line 1. Redundancy 2. Background rejection (especially beam-gas) IP1 was definitely chosen in October 2005

7 Here the beam pipe splits in 2 separate tubes. Charged particle are swept away by magnets!!! We will cover up to y Detectors will be installed in the TAN region, 140 m away from the Interaction Point, in front of luminosity monitors

8 The TAN and LHCf box ~ ( ) cm 3 marble shielding manipulator boxes for DAQ electronic

9 ARM #1 detector scintillating fibers tungsten layers - 2 towers ( cm 2 and cm 2 ) ~47 r.l. ( r.l. tungsten layers) Energy 16 scintillator layers (3 mm thick) - 4 pairs of scintillating fiber layers for tracking purpose (two orthogonal directions) scintillators Impact point (η)

10 We used LHC style electronics and readout silicon layers ARM #2 detector - 2 towers ( cm 2 and cm 2 ) 44 r.l. (22 2 r.l. tungsten layers) 16 scintillator layers (3 mm thick) - 4 pairs of silicon microstrip layers for tracking purpose (X and Y directions) Energy Impact point (η) See TDR for details scintillators tungsten layers

11 Transverse projection of detector #1 in the TAN slot

12 Transverse projection of detector #2 in the TAN slot

13 LHCf physics measurements 1. Single photon spectrum 2. π 0 fully reconstructed (1 γ in each tower) π 0 reconstruction is an important tool for energy calibration (π 0 mass constraint) Basic concept: minimum 2 towers (π 0 reconstruction) Smallest tower on the beam (multiple hits) Dimension of the tower Moliere radius Maximum acceptance (given the LHC constraints) Simulation is used to understand the physics performances Beam test in Summer 2004 (Energy resolution)

14 Development of showers in Arm #2 E γ = 500 GeV Fluka based simulation

15 Position resolution of Arm #2 calorimeter 7 µm for 1.8 TeV photons March 22, 2006 LHCf Technical Design Report O. Adriani

16 Single γ geometrical acceptance Some runs with LHCf vertically shifted few cm will allow to cover the whole kinematical range

17 A vertical beam crossing angle > 0 will increase the acceptance of LHCf Acceptance map on P Tγ -E γ plane 140 Beam crossing angle Detectable events

18 Monte Carlo γ ray energy spectrum (5% Energy resolution is taken into account) 10 6 generated LHC interactions 1 minute exposure Discrimination between various models is feasible Quantitative discrimination with the help of a properly defined χ 2 discriminating variable based on the spectrum shape (see TDR for details)

19 π 0 geometrical acceptance Arm #2 Arm #1

20 Energy spectrum of π 0 expected from different models (Typical energy resolution of γ is 3 % at 1TeV)

21 π 0 mass resolution Arm #1 E/E=5% 200 µm spatial resolution m/m = 5%

22 Model dependence of neutron energy distribution Original n energy 30% energy resolution

23 Results of the beam test at H4 line

24 Summary 1 We will be able to measure π 0 mass with ±5% resolution. We will be able to distinguish the models by measurements of π 0 and γ We will be able to distinguish the models by measurements of n Beam crossing angle 0 and/or vertical shifts of LHCf by few cm will allow more complete physics measurements

25 Estimation of the background beam-beam pipe beam-gas answered (on Nov.16), E γ (signal) > 200 GeV, OK background < 1% answered (on Nov.16) It depends on the beam condition background < 1% (under Torr) (see details in TDR) (see details in TDR) beam halo-beam pipe It has been newly estimated from the beam loss rate Background < 10% (conservative value) (see details in TDR)

26 Background from the beam pipe

27

28 Support from CERN for Integration We had (and we will have!) continuous meetings with CERN teams General : TS/LEA Integration: TS/IC Cabling: TS/EL Cooling: TS/CV Survey (cabling): TS/SU Safety: SG Radiation protection: SC/RP ATLAS, BRAN, ZDC teams A very useful TAN integration workshop has been organized on March 10 at CERN (TS/LEA). Takashi Sako: Technical coordinator All the involved groups were present!!!! Engineering Change Request (ECR) has been submitted and approved last week: Machine people are well informed about LHCf No problems foreseen for the LHCf installation at the LHC startup Main item to be discussed is the BRAN (LUMI) interference (see later)

29 Rack, data taking and trigger *Two racks will be located at Y26-05.A1 and Y27-05.A1 at USA15 hall of ATLAS counting room *The trigger signal will be created after 1.4 µsec of the beam crossing 1 st level trigger 2 nd level trigger

30 Cables TS/LEA is fully aware of the cables stuff Demande Installation Cable (DIC) has been submitted The order is under way Cables will be pulled in the July-September period See TDR for details

31 Radiation Safety We have estimated the total radiation dose and activation of LHCf installed in the TAN The activation after 30 days of operation and 1 day cool-down at L /cm -2 sec -1 is msv/hr Remote handling procedures may not be needed We are in contact with SC/RP peoples

32 Installation plan A detailed installation plan has been agreed with TS/LEA Arm #1: 128 days from May 2006 to November 2006 Cables tray Cables Detector Manipulator Electronics Tests Arm #2: 210 days from May 2006 to February 2007, similar to #1 LHCf Arm #1 and #2 will be ready to take the first LHC data.. (Beam test of the complete Arm #1 and part of the Arm #2 is foreseen August 24 th, September 3 rd at SPS)

33 LHCf and LUMI monitor (BRAN) LUMI monitor (BRAN) inside TAN is beyond LHCf (replacing 4th copper bar) Cu Bar / ZDC LHCf Lumi IP1 LHCf Cu Bar / ZDC Lumi LHCf 44 X 0 thickness But the thickness is not uniform (diamond shaped towers, no material outside towers) LUMI Monitor see different thickness of material in different geometrical regions different response as function of the impact point position (calibration is required) reduction of the number of neutral particles hitting BRAN possible dependence of the detector response as function of the beam position? We are studying the problem of the LHCf effect on LUMI together with W.C. Turner and his group from LBNL. CERN LHC and ATLAS people are informed about these studies (see TAN integration workshop as last example)

34 Effect of LHCf on BRAN measurement The effect of LHCf on BRAN measurements has been studied in the last months by simulation Reduction of shower particles at BRAN Position dependence on beam displacement (question from machine peoples: if we shift by 1 mm the real beam, does the center of the measured neutral energy shifts by 1 mm?) Answer: If beam displacement is < a few mm, difference is < 10% LHCf itself can provide the center of neutral flux LHCf can give some info on Luminosity measurement

35 BRAN response vs beam position reduction factor for BRAN: # of neutral hadrons in the LHCf aperture / Typical reduction factor: 0.3 # of neutral hadrons in the whole aperture (inelastic interactions generated with DPMJET3 model) Arm #1 Arm #2 H.Menjo

36 BRAN response vs beam position (2) Relative change of the reduction factors for BRAN with respect to the nominal value (center of the beam: nominal one) If the position of beam center stays within a few mm from the beam-pipe center, the reduction factors do not change more than 10% Arm #1 Arm #2 1 x 1 cm 2 1 x 1 cm 2 H.Menjo

37 Determination of neutral flux center by LHCf LHCf can measure (and provide to LHC) the center of neutral flux from the collisions particles Position sensitive layers Beam test result If the center of the neutral flux hits LHCf << 1 mm resolution σ ~ 200µm

38 Summary 2 LHCf can do the proposed physics measurements (background is under control) Integration with CERN infrastructures and other groups involved is well established The interference with BRAN/LUMI measurement is under study; a smooth solution seems to be feasible LHCf can provide on-line useful information to machine people (Relative luminosity, beam position, beam-gas rate etc.) Important issue to be considered in detail from now on

39 Optimal LHCf run conditions Beam parameter Value # of bunches 43 Bunch separation > 2 µsec Beam parameters used for commissioning are good for LHCf!!! Crossing angle Luminosity per bunch 0 rad 140 µrad downward < 2 x cm -2 s -1 Luminosity < 0.8 x cm -2 s -1 Bunch intensity 4x10 10 ppb (β*=18m) 1x10 10 ppb (β*= 1m) ( No radiation problem for 10kGy by a year operation with this luminosity )

40 From H. Burkhardt TAN workshop presentation

41 LHCf possible running scenario Phase-I Parasite running during the early stage of LHC commissioning in 2007 Remove the detector when luminosity reaches cm -2 s -1 level for radiation reason and reinstall the 3 Cu bars (no activation problems) Phase-II Re-install the detector at the next opportunity of low luminosity run after removal of Cu bars (activated to 10-1 msv/hr, manipulator?) Phase-III Future extension for p-a, A-A run with upgraded detectors. Detailed running scenario should be discussed and agreed with LHCC, Machine people, Atlas people.

42 Detector # 1 Detector#2 Tungsten Japan Japan Mechanics Japan Japan Plastic Scintillators Japan Japan Scintillating fibers Japan Silicon sensors INFN Photomultipliers for scintillator Japan Japan Multianode photomultipliers for fibers Japan Preamplifiers for silicon INFN Hybrid and Kapton for silicon INFN Readout electronics for fibers (VA based) Japan Readout electronics for silicon INFN VME Interface board for fibers Japan VME Interface board for silicon INFN VME ADC boards for scintillators Japan/INFN Japan/INFN VME crate Japan INFN Low voltage Power Supply Japan INFN High voltage Power Supply for scintillators Japan Japan/INFN High voltage Power Supply for fibers Japan Budget share table Contributions from different countries Japan: Italy: 600KCHF 300KCHF France: under negotiation

43 Concluding Remarks LHCf physics measurements are extremely useful for cosmic ray physics (see LOI 2004) A huge work has been done to complete the TDR, answering to the LHCC and referees comments The detectors have been carefully optimized The integration with other activities possibly interfering with LHCf is well established (ATLAS, BRAN/LUMI, TAN related experiment, safety, cabling etc.) ECR has been approved last week LHCf will be ready to take the first LHC data