1 / 18

CMS Zero Degree Calorimeters

CMS Zero Degree Calorimeters. Laura Stiles University of Kansas 23 August 2008. Experiment Introduction CMS Experiment at the LHC. The Compact Muon Solenoid (CMS) Experiment is one of the 4 large experiments of the Large Hadron Collider (LHC) at CERN. Experiment Introduction CMS Coverage.

oki
Télécharger la présentation

CMS Zero Degree Calorimeters

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CMS Zero Degree Calorimeters Laura Stiles University of Kansas 23 August 2008

  2. Experiment IntroductionCMS Experiment at the LHC The Compact Muon Solenoid (CMS) Experiment is one of the 4 large experiments of the Large Hadron Collider (LHC) at CERN

  3. Experiment IntroductionCMS Coverage • Nearly complete angular coverage allows study of wide range of forward physics • TOTEM will measure total cross section + multiplicity detectors in front of ZDC

  4. Experiment IntroductionCMS Zero Degree Calorimeter (ZDC) • Measure neutrons and photons in Pb-Pb and p-p collisions • Identical ZDCs at +/- 140m of the collision point 140 m Each ZDC located in TAN absorber

  5. ZDC Design Tungsten to stop beam: Kinetic energy of N,  produces a shower of charged particles which make Čerenkovlight in fibers N, EM has 5 horizontal towers HAD section has 4 longitudinal towers

  6. PhysicsZDC Physics Goals Measuring Reaction Centrality • ZDC measures spectator neutrons of Heavy Ions Heavy Ion Data from RHIC

  7. PhysicsZDC Physics Goals Triggering on Ultra-peripheral Collisions (UPC) • UPCs are electromagnetic collisions of the heavy-ions when passing ~20 fm away from each other When V = ~C , flux lines collapse traverse to motion • Interesting photon-nucleus and photon-photon studies accessible At 90o field is 2750 times stronger (two Pb ions passing at 20 fm → 2 x 10^20 gauss)

  8. PhysicsZDC Physics Goals Diffractive Physics • Quasi-elastic (aka "diffractive") collisions characterized by: • (i) forward (leading) proton (surviving the interaction), • (ii) large rapidity gaps, void of hadronic production. • TOTEM Roman-Pots can be used to tag forward protons from diffractive interactions • ZDC can tag or veto (neutral) hadronic activity beyond ~8.1 → very valuable to extend rapidity-gap coverage in CMS

  9. TestingZDC Beam Tests • No injection at LHC → no data except 2006 and 2007 beam tests Hadronic Section EM Section

  10. Response to Positrons Resolution agrees with simulation. A.S.Ayan et al., CMS IN2006/28 EM right EM left 50 GeV Number of Events ~12 % EM2 Signal

  11. Response to Hadrons HAD vs EM Hadronic Signal 300 GeV EM Signal 21.5% (The energy resolution was obtained by Landau fit)

  12. Current StatusZDC Installation and Testing • Right and Left ZDC installed in TAN • Laser injection system used to debug electronics chain • Currently, we are working on integrating the ZDC into the CMS system • Injection of CCW beam September 10th • ZDC should see photons from beam gas collision

  13. Current StatusZDC Beam Tuning • Luminosity Monitoring • Van der Meer Scans to obtain relative luminosity measurements • ZDC information will be used with other LHC detectors This was used at RHIC to get measurement to 5%. CMS will use the forward calorimeter, ZDC and other detectors to make a 2% measurement.

  14. Summary • ZDCs help meet very important CMS goals: • Luminosity (p-p, Pb-Pb), • Heavy-ions physics (centrality, triggering: UPC, ...), • Diffractive/forward physics (extended rapidity-gap, ...) • Beam tests showed acceptable performance • ZDCs are installed, debugged and being integrated to CMS • Next step will be LHC beam tuning with aid from ZDC • One proton beam will be circulating September 10th

  15. EXTRA SLIDES

  16. ZDC Acceptance • CMS ZDCs are located 10x further from interaction point than RHIC ZDCs, but beam is 30x more energetic at LHC • CMS ZDC has 9x greater acceptance (3x in Px and 3x in Py)

  17. Acceptance for spectator neutrons Beam crossing angle shifts Px acceptance away from zero • neutron • proton KE=200MeV Py MeV/c RHIC 62GeV RHIC 200GeV CMS 5.3TeV

  18. Current StatusZDC Beam Tuning EM section is sensitive to p-p bremsstrahlung with Ephoton>20GeV X  Luminosity is proportional to rate of coincidence Crossing angle tan()=(Xleft -Xright)/240m Average X = Xleft +Xright Z of interaction = c* (Tleft -Tright) For pHe √S = 100GeV so ZDCs should see something

More Related