E. Robutti TOTEM T1 Engineering Design Review CERN, March 7, 2006 CSC detector requirements and perfomance Enrico Robutti I.N.F.N. Genova

E. RobuttiTOTEM T1 EDR, March 7, The T1 telescope oMain physics context: measurement of the total pp cross section  Placed inside the CMS muon end-caps, around the conical section of the beam pipe at  = m 10.5 m IP T1 CMS muon end-caps  Primary goal: detect particles from inelastic scattering processes (including single-diffractive and double-diffractive events) in the region 3.1 < |  | < 4.7

E. RobuttiTOTEM T1 EDR, March 7, General requirements  Large geometrical (  -  ) acceptance in the allocated region oAt “TOTEM” running conditions (up to cm –2 s –1 ): –Close to full efficiency –Trigger capabilities –Bunch crossing determination (≥ 75 ns - spaced bunches) –Machine background rejection  vertexing capabilities  good position resolution –Radiation-tolerant detector and read-out electronics oAt “CMS” running conditions (first three years at ~10 33 cm –2 s –1 ): –Resistance to aging (with chambers mostly off)

E. RobuttiTOTEM T1 EDR, March 7, General structure oTwo symmetric arms, each with five planes of multi-wire proportional chambers with cathode strip read-out (CSC) –split in two half-arms, independently sliding on the support structure oEach plane made up of 6 independent trapezoidal CSC: –overlapping edges to have complete azimuthal coverage; –planes slightly rotated with respect to each other

E. RobuttiTOTEM T1 EDR, March 7, Mechanical support and services oA support structure with rails will be fixed to the CMS end-cap –A mounting tool with counterweight will be used for insertion oExternal structures (one per each half-arm) will be used to support the detector outside CMS and to provide all services (HV, gas, electronics routing) through a platform

E. RobuttiTOTEM T1 EDR, March 7, Chamber design oDesign similar to CMS muon chambers oChamber volumes: –10 mm gap; –10 different sizes (two smaller chambers in each plane to make place for rails) oAnodes: –30  m Ø gold-plated tungsten wires; –pitch: 3 mm; –tension: 120 g oCathodes: –gold-plated copper strips on both planes at ±60° –pitch: 5 mm; oGas: –Ar/CO 2 /CF 4 mix (possibly same as CMS) y u v

E. RobuttiTOTEM T1 EDR, March 7, Chamber mechanical structure honeycomb panel to ensure rigidity cathode plane PCB with cathode strips and anode HV and R/O lines gas frame G11 external frame with gas lines ground plane wire-holder PCB with wire connections

E. RobuttiTOTEM T1 EDR, March 7, Chamber production oSuitable Companies have been found for production of all chamber components oChamber assembly and QC will be done at PNPI in Gatchina, Russia cathode and ground planes wire-holdersgas frames gas and wire panels honeycomb panels wire electrical components etc chamber assembly/QC full test External Companies PNPICERN

E. RobuttiTOTEM T1 EDR, March 7, Chamber read-out oAll wires and strips read out independently (only some outer wires might be grouped for convenience) oBoth wires and strips will be read out digitally –A peak-finding algorithm (à la CMS) will be used to increase cathode-view resolution and separate nearby hits  Trigger primitives formed from  -wise groups of wires

E. RobuttiTOTEM T1 EDR, March 7, Chamber parameters Chamber Height of active area (cm) Length of longest wire (cm) N. of wires N. of strips per plane 1G G G G G Gap thickness (mm)10 Wire diameter (  m) 30 Wire pitch (mm)3 Strip pitch (mm)5 General parameters Chamber-specific parameters (only “large” chambers)

E. RobuttiTOTEM T1 EDR, March 7, CERN test beam, oFour (three in 2003) large CSC (from different productions) oGas mix Ar 50% /CO 2 50% o120-GeV pion beam with different bunch patterns oAnode read-out based on CMS electronics (digital); cathode read-out based on ALICE electronics (analogic)

E. RobuttiTOTEM T1 EDR, March 7, Genova test stand oQuick change of configuration of prototype chambers oAr/CO 2 or Ar/CO 2 /CF 4 gas mix available oDirect inspection of signals through digital scopes oNow equipped with hardware/software tools from Alice for read-out of a whole chamber oUsed for both detector and electronics test

E. RobuttiTOTEM T1 EDR, March 7, Anode and cathode signals Gas mix Ar 50% /CO 2 50%; HV: 3.3 kV anode cathodes

E. RobuttiTOTEM T1 EDR, March 7, Gas gain oThe gas gain can be calculated from the measured deposited charge on cathodes:

E. RobuttiTOTEM T1 EDR, March 7, Efficiency and signal/noise Anode efficiency Cathode efficiency (threshold 3  ped ) oClear plateau regions show up in both anode and cathode efficiency oThe working point can be chosen by looking at the efficiency as a function of S/N Cathode efficiency vs. S/N

E. RobuttiTOTEM T1 EDR, March 7, Time resolution oMeasurements done with TDC in test beam oJitter for single wire ~100 ns oBetter time determination by use of coincidence logic Single wire time distribution Time distribution for second wire in 3/3 coincidence

E. RobuttiTOTEM T1 EDR, March 7, Position resolution oIf digital readout with half strip determination is used, expected resolution is (5 mm)/√12 ~ 0.7 mm oPreliminary results from simulation: –half-strip peak finder   u ~ 0.7 mm; –fully digital (whole clusters)   u ~ 1.5 mm; –substantial improvement in hit loss and ghost hit rejection with half-strip method in high multiplicity events oBest u-view resolution obtained in test beam with the “center of mass” method for the strips is ~0.4 mm

E. RobuttiTOTEM T1 EDR, March 7, Chamber ageing  Recent particle flux calculations by M. Huhtinen  (integrated charge) / wire for 3 years at L = cm –2 s –1 (gain 3  10 3 ): (dQ/dl) max ~ 1.5  10 –3 C/cm;  Studies on CMS chambers: 1 cm gap CSC, Ar 30% /CO 2 50% /CF 4 20% mix, 50  m  wires: –After 13.6 C/cm: gain stable (  wires OK); current increased (cathode deposit)  Studies on LHCb chambers: 5 mm gap MWPC, Ar 40% /CO 2 40% /CF 4 20% mix, 30  m  wires: –After 0.5 C/cm: currents stable; wires OK; small surface defects from fluorine o  there seems to be a safety margin for T1 –However PNPI will conduct dedicated tests on prototype chambers

E. RobuttiTOTEM T1 EDR, March 7, Summary oDetector choice for T1: large cathode strip chambers with 3-view read-out –well known technology; –meet low-luminosity running requirements oSeveral prototypes built: –performances measured on test beam; –working test stand in Genova oChamber design finalized: –production in PNPI; –actual running parameters to be tuned on pre-production chambers

E. Robutti Extra slides

E. RobuttiTOTEM T1 EDR, March 7, Chamber assembly

E. RobuttiTOTEM T1 EDR, March 7, Gas frame

E. RobuttiTOTEM T1 EDR, March 7, Gas panel

E. RobuttiTOTEM T1 EDR, March 7, Wire-holder

E. RobuttiTOTEM T1 EDR, March 7, Wire panel