Deppner, I.

Frühauf, J.

Herrmann, N.

Kis, M.

Loizeau, P.-A.

Petris, M.

Petrovici, M.

Simon, C.

Xiang, C.

GSI Repository

RPC test with heavy-ion beams∗C. Simon1, N. Herrmann1, I. Deppner1, P.-A. Loizeau1, J. Fru¨hauf 2, C. Xiang1,3, M. Kisˇ 2, M. Petris¸4,M. Petrovici4, and the CBM-TOF working group1Ruprecht-Karls-Universita¨t, Heidelberg, Germany; 2GSI, Darmstadt, Germany; 3Central China Normal University,Wuhan, China; 4NIPNE, Bucharest, RomaniaThe Time-of-Flight (ToF) wall of CBM, conceptualizedon the basis of high-resolution timing Multi-gap ResistivePlate Chambers (MRPC), is intended to account for con-cise hadron identification at an unprecedented event rate of10 MHz. For the layout of the outer wall, strip-MRPCs areforeseen [1]. To explore the performance and limitations ofthe current design, high-rate tests with GSI/SIS-18 heavy-ion beams irradiating the full surface of a 30 × 30 cm2,fully differential multi-strip MRPC demonstrator [2] havebeen performed in the fall of 2012. In order to test theequipment under realistic conditions, data were taken fromseveral heavy-ion reactions (Kr+Pb, Ni+Pb, D+Pb) at beamenergies of 1-2AGeV with particle fluxes on the detectorsurface between 50Hz/cm2 and 20 kHz/cm2. In this re-port, we present preliminary results from the Ni+Pb beam-time in early November 2012, where the incident particleflux amounted to ∼ 50Hz/cm2.The testbeam setup (cf. Fig. 1) consisted - lookingdownstream - of a diamond start counter, the target, twoplastic counters of size 2 × 2 cm2 for cross checks, theMRPC demonstrator and a reference MRPC constructed bythe Bucharest group [3], enabling us to determine the effi-ciency and timing resolution of the demonstrator againsta substantial area (85 cm2) of the reference counter. AFigure 1: Testbeam setup in November 2012.calibration scheme, based on ROOT and Go4, adjusted tothe layout of the prototype is currently under development[4]. First, hits are built and clustered in both the demon-strator and the reference counter. Then a matching algo-rithm assigns the geometrically most suitable pendant inthe demonstrator to clusters originating from one-clusterevents in the reference counter. We find that our demon-strator is capable of dealing well with multi-hit exposure(cf. Fig. 2 left), facilitating the study of inter-hit dependen-cies. Furthermore, we studied the counter response in terms∗Work supported by EU/FP7 HadronPhysics3 and BMBF 06HD7141I.Entries  8526Mean    1.732RMS     1.118cluster multiplicity0 2 4 6 8 10 12 14 16 18 20counts110210310Entries  8526Mean     2.32RMS   0.9052cluster size [strips]0 2 4 6 8 10 12 14 16 18 20counts110210310Figure 2: Cluster multiplicity (left) and cluster size (right)of the demonstrator.of the cluster size (cf. Fig. 2 right), which averages at about2.3 strips. On the strip level, we found the resolution of thecluster mean time difference to be 80 ps (cf. Fig. 3), whichapproximately translates into a single-counter timing reso-lution of 57 ps for our demonstrator. This promising resultwas achieved so far only for the small area (4 cm2) coveredby the plastic counters, that were requested to have cleanconditions. The analysis of the efficiency as function of thehit rate on the counter surface, a task of utmost importance,is in progress.Entries  7493Constant  361.6Mean      0.5917Sigma     80.16)/2 [ps]BUCR+tBUCLt()/2 - RHD + tLHDt(-800 -600 -400 -200 0 200 400 600 800counts110210Figure 3: First hint at timing resolution on the strip level.References[1] I. Deppner et al., A CBM Time-of-Flight outer wall layout,this report[2] I. Deppner et al., Performance of large area MMRPC proto-type, 2011 report[3] M. Petris¸ et al., Towards a real size RPC cell for CBM RPC-TOF, 2011 report[4] P.-A. Loizeau et al., Status of the CBM TOF free streamingelectronics chain, this reportPHN-NQM-EXP-37 GSI SCIENTIFIC REPORT 201266

RPC test with heavy-ion beams

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RPC test with heavy-ion beams

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