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

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:CO2:N2)

Modifications

Aim Drift field 400 V/cm Resolution 0.1 ‰ Measurement of

drift velocity and gain

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 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

-9.86 kV

241Am

Far signal

AK

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 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

E [

V/c

m]

E [

V/c

m]

Simulation of field cage

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

old new

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

Simulation of Pickup detector newold

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

Simulation of Pickup detector

old new

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

Simulation of Pickup detector

newold

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 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 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

9.0 9.5 10.0 10.5 11.0

4.0

4.5

5.0

5.5

6.0

N2 (

%)

CO2 (%)

2.4502.4792.5082.5382.5672.5962.6252.6542.6832.7132.7422.7712.800

Drift velocity

9.0 9.5 10.0 10.5 11.0

4.0

4.5

5.0

5.5

6.0

N2 (

%)

CO2 (%)

200.0

223.3

246.7

270.0

293.3

316.7

340.0

Gain

Different dependences for [CO2] and [N2]

Bragg Peak study

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

On-line display

Temp. and O2

Pressure

LV

HVHV

Pickup

Vr

Near

Far

Fan-in/Fan-out

Gas outlet

Gas inlet

CA

MA

C co

ntro

ller

Discr.

FAD

C

ADCTrigger

Set-up

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

MeasurementLabVIEW display for the GOOFIE On-line Analysis

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

Long term dependence

hours

hours

hours

hours

T/P [K/bar]

P [mbar]

T [oC]

Ve [cm/s]

Blue – corrected Ve

Black – ON-line Ve

Red – OFF-line Ve

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

Correction for T and P

Correction formula :

Vdcorr = Vd – p1(T/P - <T/P>)

T/P [K/bar]

Vd [cm/s]

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

Drift velocity resolution

Mean : 2.5415 0.0002Sigma : 0.0022 0.0002

Resolution: 0.87 ‰

First try!

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

Gain vs time dependence

hours

hours

hours

gain [a.u]

gain [a.u]

gain [a.u]

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 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 implementthe system into the DCS

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 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 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

Backup

Simulation of drift velocity

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

Bragg Peak study

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 Progress with the TPC gas monitor Dariusz Antończyk

Fit functions

ALICE TPC Collaboration Meeting, Cagliari 16-17.05.2004 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