1. 1 ADAMAS Dec 2012 Piotr Koczoń,GSI Start Detector for TOF@CBM@FAIR - observation - simulation - realisation P.Koczoń / DetLab GSI Helmholtzzentrum für Schwerionenforschung GmbH

2. 2 ADAMAS Dec 2012 Piotr Koczoń,GSI CBM@FAIR 2018?

3. 3 Compressed Baryonic Matter exp. ADAMAS Dec 2012 Piotr Koczoń,GSI TOF Target TARGET Reaction products MVD+STS

4. 4 ADAMAS Dec 2012 Piotr Koczoń,GSI Beam pipe: 2.5° TARGET BEAM Yoke: 25° outside of acceptance in acceptance OBSERVATION:backward hemisphere is full of reaction products R=30mm

5. 5 Piotr 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

6. 6 Piotr Koczoń,GSI 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 D larger than 10 fm (selected from the mbias urqmd-files) 10 fm urqmd.auau.2gev.mbias.0021.ftn14 D = impact_parameter x y central events  D = 0 fm Simulations: empty events  99% HI produce only delta electrons

7. 7 ADAMAS Dec 2012 Piotr Koczoń,GSI Ideal spherical detector 28 mm BEAM

8. 8 ADAMAS Dec 2012 Piotr Koczoń,GSI 2AGeV Au @ Au δ + Urqmd 2AGeV Au on 0.25mm Au (centr+MBias) ALL FIRST particle RMS=4ps curling δ’s CentralMinBias δ’s HOTTEST area opening circumference of 88 mm 25° Θ [deg] Φ[deg] time [ps] Tot Eloss [keV] Detector can distinguish between central, min bias and empty events (δE<10keV, holds also for a ring, or 2 discs shape)

9. 9 ADAMAS Dec 2012 Piotr Koczoń,GSI Sphere cutout (crown) geometries 8fold 1ring Θ=25-60 deg 16fold 2rings Θ=25-90 deg 60fold 1ring Θ=25-35 deg 120fold 2rings Θ=25-45 deg 240fold 4rings Θ=25-55 deg 300fold 6rings Θ=25-65 deg

10. 10 ADAMAS Dec 2012 Piotr Koczoń,GSI Urqmd pC @ 30 GeV (central), 8-fold crown Eff=50% Timing: 18ps Detector can deliver start signal for TOF with RMS ~ 20ps and efficiency ~ 50 %

11. 11 ADAMAS Dec 2012 Piotr Koczoń,GSI 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. -- 90%? d) RPC barrel/discs ? 90 % e) DIRC barrel -- 50ps? ? +/- >90%? (highly) segmented detectors!!!

12. 12 ADAMAS Dec 2012 Piotr Koczoń,GSI Conclusions: presented results let us hope that 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!)

13. 13 ADAMAS Dec 2012 Piotr Koczoń,GSI Outlook: Having a segmented detector in the vicinity of the target it should be possible to measure the reaction plane as well (subject for further smulations)

14. 14 ADAMAS Dec 2012 Piotr Koczoń,GSI

15. 15 ADAMAS Dec 2012 Piotr Koczoń,GSI

16. 16 Piotr Koczoń,GSI in the HOTTEST (red) area (in the cell of 5x10deg ->2.6x5.2 mm = 13.6 mm 2 size) 800 hits out of 1500 events -> 3.9 MHz/1 mm 2 @ 1x10 9 s -1 Au on Au Hit density Φ[deg] Θ [deg] ADAMAS Dec 2012

17. 17 Piotr Koczoń,GSI For completeness: 2 discs of R=30mm Θ [deg] Φ[deg] Z[mm] X [mm] ADAMAS Dec 2012

18. 18 Piotr Koczoń,GSI start detector properties - size: R~30 mm - rate capability: several MHz / mm 2 (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