ADAMAS Dec 2012

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1ADAMAS Dec 2012 Piotr Koczoń,GSI

Start Detector for TOF@CBM@FAIR

- observation- simulation- realisation P.Koczoń / DetLab

GSI Helmholtzzentrum für Schwerionenforschung GmbH

CBM@FAIR2018?

Compressed Baryonic Matter exp.

ADAMAS Dec 2012 Piotr Koczoń,GSI

TOFTarget

TARGET

Reaction products

MVD+STS

Beam pipe: 2.5°

TARGET

Yoke: 25°

outside of acceptance

in acceptance

OBSERVATION:backward hemisphere is full of reaction products

R=30mm

5Piotr Koczoń,GSI

Details of the FAIR-Root simulations :

- event generators: FAIR–IonGun Au on Au (for δ-electrons)

Urqmd (2 – 10 AGeV AuAu, NiNi MB and Central events)- detector: two discs or a tube- like or sphere cutout (R=30 mm) ALLWAYS with an opening allowing for 25 deg acceptance cone

- sensor material: Si (just because available as activ mat.) - target Au, Ni, C- projectile Au, Ni, p

Simulations to investigate- time resolution of the first hit - suitable detector geometry- hit density

ADAMAS Dec 2012

UQMD version: 10035 1000 10002 output_file…transformation betas (NN,lab,pro) 0.0000000… impact_parameter_real/min/max(fm): 10.98 0.00 15.82…equation_of_state: 0 E_lab(GeV/u): 0.1271E+01 sqrt(s..event# 1 random seed: 67008028 (fixed)op 0 0 0 0 1 * 0 0 0 0 0 0 0 0 0 0 op 0 0 0 0 0 0 1 0 1 0 0 0 0 2 1 op 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0

peripheral events (MB) events with impact parameter Dlarger than 10 fm (selected fromthe mbias urqmd-files)

10 fm urqmd.auau.2gev.mbias.0021.ftn14

D = impact_parameter

central events D = 0 fm

Simulations:

empty events 99% HI produce only delta electrons

7ADAMAS Dec 2012 Piotr Koczoń,GSIPiotr Koczoń,GSI

Ideal spherical detector

8ADAMAS Dec 2012Piotr Koczoń,GSI

2AGeV Au @ Au δ + Urqmd 2AGeV Au on 0.25mm Au (centr+MBias)

FIRST particle RMS=4ps

curling δ’s

CentralMinBias

δ’s

HOTTEST areaopening circumference of 88 mm

Θ [deg]

time [ps]

time [ps]Tot Eloss [keV]

Detector can distinguishbetween central, min bias

and empty events(δE<10keV, holds also for a ring ,

or 2 discs shape)

Sphere cutout (crown) geometries

8fold 1ringΘ=25-60 deg

16fold 2ringsΘ=25-90 deg

60fold 1ringΘ=25-35 deg

Urqmd pC @ 30 GeV (central), 8-fold crown

Eff=50%

Timing: 18ps

Detector can deliverstart signal for TOF

with RMS ~ 20psand efficiency ~ 50 %

Realisation (possible sensors): price time res. rate cap. rad hard efficiency a) MCP discs of R=30mm + 70ps ++ + HI? >90% HI?b) Si detectors R=30mm + + + - >90%c) Diamond det. -- <5ps ++ + >90%?d) RPC barrel/discs ? <40ps 20kHz cm2 ++ >90 %e) DIRC barrel -- 50ps? ? +/- >90%?

(highly) segmented detectors!!!

Conclusions:

presented results let us hopethat it is possible to construct a detector - which can be used as START for TOF@CBM (with time res. ~ 20 ps and 50% efficiency for p+C) - at the same time it would be a reaction detector for AuAu, NiNi (distinguishing central and min-bias react’s from empty events) - could be used as reaction tag (data flow reduction est. by factor 2 – 3!)

Outlook:

Having a segmented detector in thevicinity of the target it should be possibleto measure the reaction plane as well(subject for further smulations)

16Piotr Koczoń,GSI

in the HOTTEST (red) area(in the cell of 5x10deg ->2.6x5.2 mm = 13.6 mm2 size)800 hits out of 1500 events -> 3.9 MHz/1 mm2 @ 1x109 s-1 Au on Au

Hit density

Θ [deg]

ADAMAS Dec 2012

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For completeness: 2 discs of R=30mm

Θ [deg]

X [mm]ADAMAS Dec 2012

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start detector properties

- size: R~30 mm- rate capability: several MHz / mm2 (worst case)- first particle arrival time: RMS=10 ps

- having energy resolution of ~ 10 keV it can be used for discrimination between empty events (only delta electrons) and nuclear reactions and for centrality selection

ADAMAS Dec 2012

ADAMAS Dec 2012

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