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MULTIWIRE PROPORTIONAL CHAMBERS IN M1 AND M3 SPECTROMETERS OF CHARMED BARYON EXPERIMENT(E781) AT FERMILAB

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by

Mithat Kaya

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A thesis submitted in partial fulfillment of the requirements for the Master of

Science degree in Physics in the Graduate Collage of

The University Of Iowa

May 1997

Thesis supervisor: Professor Yasar Onel


Graduate College

The university of Iowa

Iowa City, Iowa

CERTIFICATE OF APPROVAL

MASTER’S THESIS

This is to certify that the Master’s thesis of

Mithat Kaya

has been approved by the Examining Committee for the thesis requirement for the Master of

Science degree in Physics at the August 1997 graduation.

Thesis committee:

Thesis supervisor

      • ——————————–

member

      • ———————————

member

    • ———————————


ABSTRACT

The status of the multiwire proportional chambers in the FERMILAB E781 experiment and a general description of the readout system are given.


TABLE OF CONTENTS

Page

LIST OF FIGURES……………………………………………………………………V

CHAPTER

I. INTRODUCTION……………………………………………………………………… 1

II. MULTIWIRE PROPORTIONAL CHAMBERS………………………… 3

III. MULTIWIRE PROPORTIONAL CHAMBERS IN E781…………… 9

3.1 M1 Multiwire Proportional Chambers(M1WPC)………………… 9

3.2 M3 Multiwire Proportional Chambers (M3PWC)… ……………12

3.2.1 First Lambda Chamber (M3PWC1)………. ……………13

3.2.2 Second Lambda Chamber (M3PWC2)………………….13

3.2.3 Third Lambda Chamber (M3PWC3)…………………….14

3.3 MWPC Electronics……………………….. ……………………………..14

3.3.1 Preamplifier Cards………………… ………………………….15

3.3.2 Readout System……………………. ………………………….16

3.3.3 Readout Control Logic…………………………………………23

IV. EFFICIENCY OF THE MWPC……………………………………………….25

4.1 Gas Mixture………………………. …………………………………………25

4.2 High Voltage………………………………………………………………… 26

4.3 Threshold Settings…………………………………………………………. 27

4.4 Gate Width On the Readout Electronics……………………………. 28

V. EFFICIENCY CALCULATION……………………………………………. ..29

VI. CONCLUSION…………………………………………………………………… 32

VII. APPENDIX………………………………….. ……………………………………34

BIBLIOGRAPHY.………………………………………………………. 37


LIST OF FIGURES

Page

Figure 1. E781 Experimental Layout…………………. ………………………………39

Figure 2. Shematic of one of the M1PWCs…………….. ………………………….40

Figure 3. Plane organization of the M1 and M3 PWCs……………………….. ..41

Figure 4. Mylar strips (garlands) in the Multiwire Proportional Chamber…. ..42

Figure 5. Block diagram of the readout electronics for a MWPC…………… .15

Figure 6. The relation between the actual threshold and the monitor voltage. 43

Figure 7. The block diagram of the readout control logic…………………………44

Figure 8. Efficiency vs. HV for M3PWC 1+2 with different gas mixtures….. 45

Figure 9. HV vs. Efficiency for M3PWC3 with different gas mixtures……….. 46

Figure 10. HV at 50% Efficiency vs. Isobutane Fraction for M1 and M3PWCs……………………………………………………………………………………… 47

Figure 11. Plateau curve obtained with a Sr90 source for M1PWC with

different gas mixtures……………………………………………………………………….. 48

Figure 12. Plateau curve obtained with the beam for M1PWC with

a gas mixture of 24 % isobutane 0.15 % Freon and 75.85 % argon………….. 49