1. The forward detectors of CMS Experiment at LHC Bolek Wyslouch MIT
University of Kansas, Lawrence, 22 October 2004
A collection of graphs and drawings from talks of
A. Panagiotou, K. Eggert, A De Roeck and others
October 22, 2004
CMS Heavy Ions Bolek Wyslouch

2. CMS as a Detector for Heavy Ion Physics
Fine Grained High Resolution Calorimeter
Hermetic coverage up to |h|<5
(|h|<7 proposed using CASTOR)
Zero Degree Calorimeter (proposed)
Tracking m from Z0, J/, 
Wide rapidity range |h|<2.4
σm ~50 MeV at 
Silicon Tracker
Good efficiency and low fake rate for pT>1 GeV
Excellent momentum resolution Dp/p~1% for pT<25 GeV and higher
DAQ and Trigger
High rate capability for AA, pA, pp
High Level Trigger capable of full reconstruction of most HI events in real time
m chambers
Fully functional at highest expected multiplicities
Detailed studies at ~ and cross-checks at
HCAL
ECAL
Si Tracker
including Pixels
October 22, 2004
CMS Heavy Ions Bolek Wyslouch

3. Quarter Cross-Sectional View
(RPC)
(DT)
(CSC)
Rapidity coverage: || < 2.4
4 T solenoid
Muon momentum measurement uses return field of iron yoke
October 22, 2004
CMS Heavy Ions Bolek Wyslouch

4. Zero Degree Calorimetry for CMS
Spectators
Participant Region
ZDC
ZDC
Spectators
Beam pipe splits ~140 m from IR
ZDC
LOCATION
BEAMS
12.5 cm
EM Section
Luminosity
Detector
Hadronic
Section
9.6 cm
ZDC improves resolution at large b
October 22, 2004
CMS Heavy Ions Bolek Wyslouch

5. ZDC integration with TAN
October 22, 2004
CMS Heavy Ions Bolek Wyslouch

6. CMS Heavy Ions Bolek Wyslouch
T1: 3.1 < h < 4.7
T2: 5.3 < h < 6.7
October 22, 2004
CMS Heavy Ions Bolek Wyslouch

7. CMS Heavy Ions Bolek Wyslouch
T1 – DETECTOR: LAYOUT
ALUMINIUM FRAME/SUPPORT
HALF DETECTOR SUB-ASSEMBLY
DETECTOR IN TWO HALVES, TO ALLOW INSTALLATION WHEN THE VACUUM CHAMBER IS ALREADY IN PLACE
ALUMINIUM FRAME FOR EACH CSCs PLANE (SUPPORTS ELECTRONICS, SERVICES AND LINK TO THE RAILS)
THE TRUSS/RAIL SYSTEM IS INTEGRAL PART OF DETECTOR
CSC PLANE SUB-ASSEMBLY
October 22, 2004
CMS Heavy Ions Bolek Wyslouch

8. T2 Telescope T2 5.3< lhl < 6.7 Vacuum Chamber 1800 mm 400 mm
Bellow
Castor Calorimeter(CMS) T2
GEM Telescope: 8 planes mm from IP
October 22, 2004
CMS Heavy Ions Bolek Wyslouch

9. CMS Heavy Ions Bolek Wyslouch
T2: telescope
8 triple-GEM planes, to cope with high particle fluxes
5.3<||<6.6
54(j) x 22(h) = 1536 pads
Pads: Dh x Dj = 0.06 x 0.018p
~2x2 mm2 __ ~7x7 mm2
Strips: (width: 80 mm,pitch: 400 mm)
Digital r/o pads
Technology used in COMPASS
pads
strips
Analog r/o circular strips
October 22, 2004
CMS Heavy Ions Bolek Wyslouch

10. CMS Heavy Ions Bolek Wyslouch
CASTOR SPECIFICATIONS
H CASTOR A L
Sampling Unit ~ λI ~ 2 Xo
Reading Unit=7SU ~ λI ~14 Xo (16) Sectors in φ (22.5ο) Channels (RUs)=16 x 18=288
EM = 2 RU (~ 28 Xo)
H = 18 RU (~ 10 λI)
Air-core Light Guide
APDs
Active volume
(126) W/Q-plates Sampling Units per octant
Reading Unit
5mm W-plate (octant)
2mm Q-plate (semi-octant)
Beam
October 22, 2004
CMS Heavy Ions Bolek Wyslouch

11. CMS Heavy Ions Bolek Wyslouch
CASTOR PROTOTYPE II
EM = 2EMRU = 27 Xo
H=2EMRU+4HRU=4.3 λΙ
H CASTOR A L EM H1 H2
H H4
October 22, 2004
CMS Heavy Ions Bolek Wyslouch

12. CMS Heavy Ions Bolek Wyslouch
Detector Coverage
Forward Region:
Multiplicity and hermetic coverage to |η|<7
Zero Degree Energy
Physics:
Centrality
Limiting Fragmentation
Peripheral and ultra-peripheral collisions
Low-x, Color-Glass Condensate
DCC, Centauros, Strangelets
October 22, 2004
CMS Heavy Ions Bolek Wyslouch

13. CMS Heavy Ions Bolek Wyslouch
Conclusions
Forward detectors are being designed for CMS
CASTOR
ZDC
Inclusion of TOTEM detectors in the heavy ion runs will significantly enhance forward capabilities
October 22, 2004
CMS Heavy Ions Bolek Wyslouch

14. CMS Heavy Ions Bolek Wyslouch
WHEN CMS STARTS TAKING DATA WITH HEAVY IONS THIS IS THE FIRST RESULT THAT WE WILL OBTAIN
14000
October 22, 2004
CMS Heavy Ions Bolek Wyslouch