Progress with the TPC gas monitor Dariusz Antończyk Outline : Motivation Simulations Measurements Summary & Outlook

Motivation We wish to monitor gas quality with high precision GOOFIE is a classical solution (NA49 TPC, CERES TPC, HADES MDC, STAR FTPC) We have a three component gas mixture (Ne:CO 2 :N 2 ) Modifications Aim Drift field 400 V/cm Resolution 0.1 ‰ Measurement of drift velocity and gain ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk

Drift monitor detector Progress with the TPC gas monitor Dariusz Antończyk Proportional counter modification Connected to voltage of field cage Added a wire mesh in front of the window Removed many insulators kV 241 Am  Far signal A K We have three GOOFIEs from MPI München (Dr. V. Eckardt)

Progress with the TPC gas monitor Dariusz Antończyk Drift monitor detector We replaced the HV cable and added copper rings

Simulation of field cage ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk E [V/cm]

Simulation of field cage ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk oldnew

ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk Simulation of Pickup detector newold

ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk Simulation of Pickup detector oldnew

ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk Simulation of Pickup detector new old

ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk Pickup detector Constructed by A.Radu (GSI)

Ternary gas mixture map (simulations) ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk  Different dependences for [CO 2 ] and [N 2 ]

Bragg Peak study ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk

On-line display Temp. and O 2 Pressure LV HV Pickup Vr Near Far Fan-in/Fan-out Gas outlet Gas inlet CAMAC controller   Discr. FADC ADC Trigger Set-up ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk

Measurement LabVIEW display for the GOOFIE On-line Analysis

ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk Long term dependence hours T/P [K/bar] P [mbar] T [ o C] V e [cm/  s] Blue – corrected V e Black – ON-line V e Red – OFF-line V e

ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk Correction for T and P Correction formula : V dcorr = V d – p1(T/P - ) T/P [K/bar] V d [cm/  s]

ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk Drift velocity resolution Mean :  Sigma :  Resolution: 0.87 ‰ First try!

ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk Gain vs time dependence hours gain [a.u]

ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk Summary & Outlook After applied modifications some improvements have been achieved: more uniform response of the system 400 V/cm electric field 0.87 ‰ resolution of the GOOFIE drift velocity In the nearest future further effort will be made to refine the GOOFIE resolution. This can be done by : improved temperature measurement improved gain measurement use final electronics (Luciano) and implement the system into the DCS

ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk Summary & Outlook Problems to be solved : understanding of gain dependence on various parameters (P, T, gas composition, etc.) small discharges elimination

ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk Backup

Simulation of drift velocity ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk

Bragg Peak study ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk

Fit functions ALICE TPC Collaboration Meeting, Cagliari Progress with the TPC gas monitor Dariusz Antończyk OFF- line y=p0+p1*exp(-exp(-z) – z +1) z=x-p2/p3 ON- line gauss fit