M. Bonesini - CM 22 RAL October 08

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TOF0 status

M. BonesiniSezione INFN Milano Bicocca

M. Bonesini - CM 22 RAL October 08

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problems with H6533 assemblies (mainly 15% of broken divider during tests !!!) best H6533 assemblies used for TOF0 TOF0 installed at end June 08 and in DAQ since July 08 e+ beam data used to test detector performances (thanks Yordan )

M. Bonesini - CM 22 RAL October 08

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H6533 problems problems with broken active divider on 15% of H6533 assemblies (Hamamatsu has revised it): mainly broken FETs and in addition noise

M. Bonesini - CM 22 RAL October 08

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Some examples of PMT signals

noise

distorted

M. Bonesini - CM 22 RAL October 08

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TOF0 assembly in Milano

M. Bonesini - CM 22 RAL October 08

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Preliminary installation before Q7 (July 08)

Installation in final position inside DSA

M. Bonesini - CM 22 RAL October 08

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During data taking: one broken PMT (channel # 28, it was one of 3 discharging ones as discovered from preliminary tests at RAL after transport in June)

05/08/23 M. Bonesini - CM 22 RAL October 08

The TOF results from Frascati BTF. P = 250 MeV/c (from Yordan)

obtained time resolutions of the bars in the analysed run.

Time-walk effect can be suppressed by imposing a constrain in the difference of the ADC pulse height in the bars. In the plot : No constrain (up) ,delta ADC < 25% (middle) and delta ADC <10% (down).

05/08/23 M. Bonesini - CM 22 RAL October 08

The plot presented by Jean-Sebastien shows the Time of Flight between GVA1 and GVA2 in run 690. This is the so called “positron beam”

05/08/23 M. Bonesini - CM 22 RAL October 08

The difference between the measured time in the two planes of TOF0 in run 690 (the “positron beam”). No absolute time calibration and no time walk correction. Very low statistics.

05/08/23 M. Bonesini - CM 22 RAL October 08

The same time difference but in run 684. Probably the beam is a mixture of pions and positrons. P = 300 MeV/c

05/08/23 M. Bonesini - CM 22 RAL October 08

The propagation of the particles trough the beam channel is simulated with G4beamline for pion reference momentum 444 MeV in dipole 1 and muon reference momentum 240 MeV in dipole 2. Simulated particles are used to investigate how the intrinsic time resolutions of the TOF counters affects the particle separation by time-of-flight between TOF0 and TOF1.

TOF plots with 100 (left) 120 (middle) and 140 ps (right) time resolution per PMT which gives 70, 85 and 100 ps counter time resolution.

Momentum distributions of muons, pions and electrons in front of TOF0

Simulation of the separation of muons, pions and electrons by the time of flight between TOF0 and TOF1 (from Yordan)

M. Bonesini - CM 22 RAL October 08

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Conclusions TOF0 installed since June 2008 data taken since then performances seem compatible with what obtained at BTF (no time walk correction possible) problem: will PMTs survive ??