A New Detector for Physics at HERA - III

Transcription

1 A New Detector for Physics at HERA - III CIPANP New York May 2003 Iris Abt MPI für Physik isa@mppmu.mpg.de

2 Content Detector Concept Interaction Region Silicon Tracker Calorimetry Acceptance Momentum Resolution Energy Resolution e/ð Separation Physics Reach Conclusions

3 Detector Concept Extend the rapidity range compared to existing detectors. Use a dipole field to pull scattered positrons into the acceptance. Measure F 2 and F L for 0.1 < Q² < 10 GeV² Make it symmetric Vector Mesons Forward Jets

4 Detector Concept Silicon Tracker high resolution tracking radiation resistent Silicon Tungsten Calorimetry EM good energy resolution good spatial resolution good e/ð separation R<60cm L=10m Compact Tube plus endwalls fit into dipole magnet

5 Interaction Region -5.8m +5.8m e p 1 dipole field too large synchrotron radiation fan T +0.3T Use existing 50 pb 1/year HERA I and II magnets

6 Silicon Tracking forward geometry 14 planes on each side e p Each plane is 40 x 40 cm² ² Baseline: : 2 double-sided silicon detectors plus support r=30 cm tube 0.1% X per plane 0

7 Silicon Tracking silicon planes The beampipe opens up to allow for the deflected electron beam. Detectors start at 3cm distance to the beam. Symmetric beampipe is not needed. However, one side will be used to integrate pumps.

8 Calorimetry Positron Hemisphere EM calorimeter endwall at -5.0m [might come from HERA-B] 25 x 1 X 0 EM catcher calorimeters at z=-170cm and z=-90cm 25 x 1 X 0 EM barrel calorimeter covering z=±70cm 50 x ½ X 0 EM catcher calorimeters at z=+90cm and z=+170cm 25 x 1 X 0 25 x 1 X 0 Proton Hemisphere EM and hadron calorimeter endwall at +4.8m [might come from ZEUS] Baseline is silicon tungsten.

9 Calorimetry z= cm radius = 40cm radius = 60cm eta [-2.4,-1.8] [-1.8,-1.3] [-1.3,+1.3] [+1.3,+1.8] [+1.8,+2.4] y-z view The center is a bit packed. No tracking for eta < 1! But good calorimetry!

10 Far Out Components Proton Remnant Tagger hadron calorimeter plus silicon strip detectors at +20m diffractive and exclusive processes Photon Calorimeter electromagnetic calorimeter at -100m luminosity from ep tagging of ISR Spectator Calorimeter hadron calorimeters above and below beamline at +100m identify spectator nucleon in e d scattering Details after design of beamline

11 Acceptance depends on energy rapidity azimuth angle

12 Acceptance for 3 hits per track focus on low Q² central region for 4 hits per track forward region

13 Momentum Resolution x multiple scattering 2.9% standard Gaussian Sigma 2.93 percent Bremsstrahlung (pgen-prec)/pgen Full GEANT3 simulation [atlsim] The system is not limited by the intrinsic resolution of the silicon strip detectors.

14 Bremsstrahlung with beampipe without beampipe GeV positrons eta = -3 on endwall

15 Momentum Resolution Electron Momentum Resolution % no material x10 2.3% no supportl ideal Gaussian Sigma 0.68 percent extra-light Gaussian Sigma 2.24 percent (pgen-prec)/pgen (pgen-prec)/pgen x10 2.6% no beampipe 2 x % no dreams light Gaussian Sigma 2.59 percent standard Gaussian Sigma 2.93 percent (pgen-prec)/pgen (pgen-prec)/pgen A creative beampipe can help with the tails. And one can use Bremsstrahlungs - Recovery Pretty hard to build silicon stations with less material.

16 Momentum Resolution dp/p, eta vs phi rapidity azimuth 0 Improvements through software better plane - placement material reduction

17 /E Energy Resolution EM Calorimeter end of barrel 15% E 2% center of barrel 14% E 2% The catchers and the endwalls should be similar to the end of the barrel.

18 Electrons and Pions 5Gev Positrons 5 GeV Pions

19 Energy Response e ð e ð GeV Less of the hadronic energy is seen

20 e/ð Separation efficiency rejection easy above 5 GeV energy/momentum > 0.9

21 e/ð Separation eta=1 eta=0 20 eta=0 eta=1 20 eta=1 eta=0 20

22 e/ð Separation rejection power Ee=2GeV eta=1 eta=0 50 rejection power rejection power Ee=3.5GeV efficiency Ee=5GeV eta=0 eta=1 efficiency eta=0 eta= efficiency 50 50

23 Q² (GeV²) Kinematic Range electron + jet (Ep=460GeV) + jet (Ep=920Gev) for F 2

24 High x Range pb Ep=920GeV Ep=460GeV

25 F L Ep=920,690GeV Ep=920,460GeV

26 Forward Jets H1 and ZEUS coverage HERA -III coverage Large extension of jet coverage

27 Status Physics Program Conceptual Detector Design GEANT 3 Simulation Letter of Intent wwwhera-b.mppmu.mpg.de/ hera-3/index.html There is a lot left to be done

28 Conclusions A detector especially designed to extend the currently probed kinematic range in e p scattering can facilitate an exciting physics program. This can happen at a modified HERA machine or elsewhere. Let s hope it doesn t get worse.