Particle Identification in CBM

● Geometry and acceptance at 25 AGeV

● Hadron identification

- TOF performance

- Matching to the Silicon Tracker

● Summary

K. Wisniewski, FOPI Coll., Uniwersytet Warszawski, Universität Heidelberg

Silicon tracker - p determination- sec. vertex

Electrons - RICH, TRDHadrons - Time of Flight (RPC)

Geometrical acceptance : lab 5 – 30o

(New) CBM Geometry

• Hadron identification up to 5 GeV/c• K/ separation up to 5 GeV/c large distance from the target large scale (high cost)• High-rate capability (up to 20 kHz/cm2)• Good time resolution

Phase-space Distribution at 25 AGeV

•TOF wall located 15 m from target

• K,yields from UrQMD, Au+Au,25AGeV

• S/B depends on TOF resolution

• Required S/B for K : 10

• K/ separation with 80ps device: up to 4 GeV/c

Hadron Identification by TOF

●Good mid-rapidity coverage●D0 detectability as low as 10% (p

max=4 GeV/c)

●Factor 3 better with pmax

=6 GeV/c

As good as poss. time resolution needed

D0 Efficiency

FOPIStrip-Anode

ALICEPad-Anode

• Very good time resolution• Negligible tails• High efficiency• High granurality• Low cost• High-rate capability is a problem (2 kHz/cm2) A4 glass geometry optimisation• Ageing needs to be tested

Timing Multi-gap Resistive Plate Chambers

● Extrapolation over 5 m. of RICH● Perfect position resolution assumed

•Matching distorted due to mult. scattering•Accuracy of the extrapolation depends on distance

Matching to the Silicon Tracker

●Hit-search radius 2x,y

(86% efficiency): 20.18cm (1 GeV/c)

20.09cm (2 GeV/c)●Biggest confusion close to the target (Silicon) and at small angles (5o)●Double hit probability at 5o: 15% (1 GeV/c) 4% (2 GeV/c)●Misidentification probability (15%)/2 (with no background particles)

Efficiency and Misidentification

● PID needs a good tracking system (avoid large gaps)

optimisation of RICH (splitted into two parts)

tracking on the way to TOF (additional TRD stations)

● TOF-based PID limited to 4-6 GeV/c (for K/ separation)

● Good coverage of the D0 phase-space distribution (mid-rapidity)

● D0 efficiency 10-30% (depending on pmax)

go for as good as possible TOF resolution

use other technique for the K/separation at high p (RICH?)

Summary

Monolithic Activ Pixel Sensors (MAPS)

•Excelent hit resolution (3 m)•Small thickness (20 m)•Not radiation-hard•Slow readout