Fermitab TM-954 2562.000

M. REX!

Fexmi National Accelerator Laboratory Batavia, Illinois

April 1, 1980

Proportional wire chmbersanddriftchmbersarediscussed

in their applications to high energy particle physics. Sme

results frorr'a resistive catkxle c2xmber and new ideas are

There have been such a variety of wire chambers built in the recent

years, thatithasbeccmzdifficultto selectthetypzwhichmybermre

suitable for an experiment.ti design, Theaimofthispaperistodiscuss

mne imprtant aspects of proportional wire chambers and drift ch&rs with

the hope that it could bs useful in decision making, Q%re spark chambers

are excluded in this discussion since they are wzll understaxl, and their

usage has be- limited. The mltistep avalanche czhaGxrswillalsobe

excludedherebeeause~y~~notlbeenu~inexper~ts.

*Stitted to 1980 Vienna Wee Chambep Conference

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Proportional chamber and drift chamber technology has developed rapidly 1 2,3)- sinceitwasintrokced .' to high energyparticle physics instrumentation

with the parallel development of integrated circuit technology, but* are

having difficulties in catching up with the development of new accelerators

which have produced higher and higher energy particles at increasing rates.

The collisions of these very high energy charged particles produce large

multiplicities. Fermilab is constructing a bp colliding beam facility that

will produce center of massenergy of 2 TeV. Eixpected average charge multi-

plicity at this energy is about 40. Particle identification and track pat-

ternrecognitionof46 chargedtracksisaverychallengingproblem.

~ProportionalChambers

Proportionalwirech&z)ers (PWC's) arebecominglesspopuk%rdueto their

limited spatial resolution and the high cost of large nunbers of wires for

large detector systems. They may still be best for handling high rates 4,5,69

inadlarea. Because of the one dimensional readout nature of X's,

aminimum of 3wireplanes~mustbe used indeterminingthecoordinates of

more than one simultaneous track to resolve x-y artibiguities. Fig, 1 shclws

a typical experimantal arrangement of (u, y, v) PK.planes. x-y mnbiguities

may not be ccanpletely resolved even with the .addition of 'the third plane

when track multiplicities are large*‘ Fig. 2-shows the nurber of tiiguities

asafunctionofthenur&rofsimultaneoustracks. 3

An importantdevelopmentin the usage of PIE's has been the detection

of induced pulses by cathode strips or wires which provide a precise deter-

mination" of the avalanche positicm along the anode wire (Fig. 3), Cen-

troid determination of the induced pulses provides better than 100 u resolu-

tion fornormaltracks. Anoptknrngeometryfor stripcathcdes canbe

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Calculatedg9 for achieving better resolutions. The electronic noise is the

amin resolution limiting factor for this type of chamber, Although it pro-

vides a hi-dimensional coordinate (x, y) readout, the coordinates are not

correlated to each other for each track, thus it requires a third coordinate

(u9 rruaasureknt to resolve x-y artbiguity for multiple tracks. Figures 4a

and 4bshcw2typicalarrangemantsmade forCEJX0 109 and TASS0119. A oz =

400 p was obtained by & and a considerably less accurate cz resulted

fra the TASS0 proportional chambers, 90° strips do provide better resolu-

tion for the same strip width. As the angle is decreased fram the 9Oo, the

resolution gets mrse. Electronic noise may be the main factor for limiting

the resolution when the strips are long and kqxxfectly shielded,

At Fennilabwe have investigat cdl' 2 asimilarbi--dimensionalEWCusing

resistive cathodes of In-Sn oxide film. !The induced charges were detected

by pri.&ed circuit copper strips outside of the chamber volutne as shown in

Fig. 5. There is a 125pm thickmylar sheet in between the resistive film

and the copper strips. Icxd change in the charge distribution on the resis-

tive film is detected by the copper strips as the positive ions move away

fromtheavalancheposition. Anotherwayofsayingthisisthatthelocal

voltage drop in the resistive film is coupled to the copper strips capaci-

tively* Thecentroidofthe inducedchargedis~~~onob~~fraknthe

strips provides an excellent determination of the avalanche position along

the wire. A. Michelini, VERY, 139 used this technique for obtaining a trigger

~ntoallwires inaplane. Recently agroup149 f obtaineda second

axrdinate from strips outside of resistive cathode tubes.

-4-

The.resistive film that is used by the Fermilab group is made by Sierra&n

Ccarrpany, California. A gas mixture of 50% A-SO% C2H6 was bubbled through

ethyl alcohol at O" C for obtaining the following results.

Fig. 6 shc~s a histogram distribution of the centroids ustig collimated 55 x-rays from a Fe source. Thewidthofthecollimatorwas 825 pm. The full

width (FWHM9 ofthedis~~u~onagreeswellwith'~ewidthof the source.

The distribution has a flat top within the statistics. The edges of it would

give us an upper limit of 120 urn for the spatial resolution of avalanche posi-

tion along the anode wires. Fig. 7 shy the centroid positions as a func-

tion of the precisely measured source positions. The linearity is excellent,

and the average deviation from the straight line is less than 100 m.

The main objective in the developt of the resistive cathode PKC is

to construct a resistive cathcde pad chamberw]nichcanhandlelargenMbers

of simultaneous tracks at high rates in a relatively small area. A schematic

picture of the high rate pad choker is shown in Fig. 8. S&l anodewire

spacing, 1 mn, assures good time resolution. 0ur earlier resultsf5) obtained

frcm lnm anode spacing show (Fig. 9) that a time jitter of 11 ns at full

widthathalf maximumis achieved. A 30 ns gate width assures good efficiency.

The rate capability of an anode wire is about 10' cm-" see-' along its

l.engttl169 using a sensitive amplifier-discriminator~circuit. The space

charge limits thechambergain. Charge pile up problems may limit arrplifier-

discriminator front end circuitry in its rate capability &en the rate ex-

ceeds 5 x lo5 cm -1 sec-l although a 10 cm long wire can handle rates of lo6

SX! -1. Thiswouldnotbe aproblemwha10 independentpadsobservethe

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avalanchesalongthewixe asinthis scheme. The distribution of charges

collected fromthepads indicatethehitwire andtheavalanchepositionalong

the wixe. The electmnic noise for each pad charmel should be small due to

the small capacitance of each pad.

The chargeobtainedfrcmeachpadcanbedigitizedbyaflashADC. 17)

(FADC) and storedintoamemryevery 32 nsuntilaninterestingevmtis

found. Thenthe cen~oidofthechargedistribution along thewire &&ain.&

3 pads co&ribu&),measures the avalanche position along the anode wire. As

we have seen from the strip chamber results, this coordinate can be measured 4

toanaccuraqofbetterthan I.20 m. ~centroidofthechargedis~~u~o~

~~onal.tothewiredete~esthehitwire. Acareful look atthisdis-

tribution could give us.which side of the wire the avalanche occurred. The

accuracy of this coordinateisth~measuredtoabouto;ms= 300 pm (l/J12

for wire spacing of lmn). This x-y coordinate mea .suremnt is completely

unambiguous and provides space points for all resolvable simultaneous track.

FADc's speed of 32 ns, matching the gate width of 30 ns, gives us a rate

capacility of > 3 x lo7 counts per second for an area of 10 cm x 10 cm for a

largenu&erofsimultaneoustracks.

Drift Chambers

Drift chambers have become the rmst tidely.used w&re chambers since

they were introduced to high energy physics ins~tation 2f39 by the G.

C--F. Sauli and J. Heintze-A. H. Wa%snta groups. Drift chambers have

taken a variety of shapes and dimensions since. Historic develo-t is well

smmarized by J. Heintze 18) . Only certain aspects of driftcham&rswill be

discussed in the follow+Ig.

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Drift chambers provide high spatial resolution16) , 100-200 rim at aixos-

@eric pressures. A carem study of drift velocity as a function of the

199 electric field can improve the resolution to SO-80 vrn foradriftspacing

of 2 cm. Spatial resolution of 20 urn are obtainable at high pressures2".

During the last few years, exciting high energ.. physics experiments have

been carried out using colliding beams at SPEAR, DORIS, ISR, PETRI, and Cor-

Ileli. More experiments are planned at PEP,

energy, Fermilab pp at 2 TeV, and ISAEZXE.

merits, largely drift chm&ers, cover almost

large numbers of simultaneous tracks (up to

CERN Fp at 540 GeV center of IMSS

The detectors for these experi-

4fl steradiansanddetectrather

40 charge tracks on the average).

Space point determin ation of tracks help improve pattern recognition and

save a great deal of computing time. A. Wagner from the JADF?19 experiment

reported that correlated hi-dimensional coordinate determination untangled

coqlicated events.

Mainly there are 2 techniques for obtaining correlated hi-dimensional

ooordinate readout with drift chambers, charge division 22,23) and delay-line

readout24) .

Sczx charge divisicm and delay line

ma&al groups are li&dinTablesland

lines provide about a factor of 4 better

division.

division.

atie wires,

resolution

It is not clearly understood whatlimits the resolution in charge

Electronic noise, cross-talk between the sense wire, and the cath-

and reflections due to imperfect te rminationcouldbe scmeofthe

limiting factors in the charge division readout technique. It

results published

2. They indicate

resolution on the

by various experi-

thatthedelay

average than charge

appears that signal to noise is the major factir in limiting the resolution

for the delay line technique.

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The noiselimitfactor caJ.culatedusingV. Radeka's formula 259 for

Femrilablsprintedcircui.tdelaylinedriftchamberis ingoodagreemantwith

the obtained results.

.‘cF .e .$i 2.46 - 'CD ZonQD

l/2 =F

The parameters for the Fermilab delay-line drift chambers are:

TF = ‘30 p!3, 'CD = 277 ns/l.S m, 2, = 85Q, and QU = 3 x 10' e".

%zns = 0.2% of the length of the line, giving aarms = 3 mn.

Multitrack Resolution

How do these mxt camnonly used correlated hi-dimensional drift chambers,

ane using charge division and the other using delay line readout, ccxrpare in

two-track resolution? One way to answer this question is to ccanpare confusion

(or dead) region around the anode wires during the detection of a track by

thetwotechnigues.

Using the charge division technigue, the charges from each end of the

&ale wire are integrated for about 150-200 ns for obtaining a crms resolu-

tion of 1% over the wire length. This results.in a 2 L an2 (where L is the

wire length) of confusion area for an electron drift rate of 200 ns/cm in

the gas. This‘is schematically shcxn in Fig. 10.

For the delay line technique, let us take Ferxtilab drift chambers using

the printed circuit delay line. Thisdelay line produces pulses of 6 ns rise

tin-e. with a full width of less than 50 ns into 85 52 impedance (characteristic

impzdance of the delay line) using 50% argon - 50% ethane gas, bul&led through

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ethyl alcohol at.O" C (about 5% admixture of ethyl alcahol9. It is a bal-

anced line, and the measured noise into 85 0 is less than 30 $7 through a

balancedtounbalancedtransfo~whichcancelscomrmn mde noise.

Inthis case, theresultsare~~catedinpig.11. !Phemximumcmfu-

sion area is 1.5 cm2 which is less than 1% of the area of the charge division

case. The double pulses obtained from each end of the delay line are resolved

intimeiftheycomeaboutaminimumof50nsapart. This impliesaminimm

track separation of 2.5 m with the electron drift time of 200 ns/cm in the

g-*

TM-954 -9 -

'Fddtricites

1. G. charpak, R. Bouclier, T. -Bressani, J. Favier, and C. Zupancic, Nucl. ~nstr. and Meth;"62- (19689 262.

2. G. charpak, D. R&m, and H. Stein=, Nucl. Instr. and Meth. 80 (1970) 13.

3. A. H. Walenta, J. Heintze, B. Schurlein,. Nucl. Instr. and Meth. 92 (19709 - 373.

4. W. Frieze et. al., Nucl. Instr. andMeth. 136 (1976) 93.

5. R. Hamnarstron, 0. Runolfsson, and M. Uldry, 1980 Vienna Wire Chamber c!onfexence~ Regort.

6. R. J. Gray, 1980 Vienna Wire ChamberConferenceReport.

7. R. Baja, Fermi. National Accelerator Laboratory, private cxmmnication.

8. G. Charpak and F. Sauli, Nucl. Insti. and Meth. 113 (1975) 381.

9. E. Gatti, A. Longoni, H. Okuuo, and P. Semenza, Nucl. Instr. and Meth. 163 (1979) 83-92.

10. Private commnication with the 0 Group.

11. Private -cation with the TASS Group.

12. M. Atac, Fermilab Internal Report TM-932 (Janua?q 1980) and &I. Atac, D. Hanssen, and J. Urish, will be published.

13. A. Michelini, CEFN, private mmunication.

14. G. Battistoni, E. Iarocci, G. Nicoletti, L.-Trasatti, report& at the 1980 Vienna Wire Chax&er Conference.

15. M. Atac, IEE??, Txms.‘Nucl. Sci. No. 3, Vol. NS-19 (1972) 144. : .

16. A. Breskin, G. Charpak, F. Sauli, M. Atkinson, and G. Schultz, Nucl. Jhstr. andMeth. 124 (1975) 189.

17. B. Hal$ren and H. Vemeij, IEEE-Fans. Nucl. Sci.

18. J. Heintze, Nucl. Instr. and Meth. 156 (19789 227-244.

19. N. A. Filatova, T. S. Nignmiov, V. P. Pugachevich, V. D. Riabtscv, M. D. Shafranov, E. D. Tsyganov, D. V. Uralsky, A. S. Vodopianov, F. Sauli, and M. Atac, Nucl. In&r. and Meth. 143 (1977) 17-28.

TM-954 -to-

20. W. Farr, J. Heir&e, K. H. Hellmbrand, and A. H. Wale&a, Nucl. Lnstr. and Meth. '154 (1978) 175-181.

21. H. Drunm, R. Eichler, B. Granz, J. Heintze, G. Heinzelmmn, R. D. Heuer, J. Von Krogh, P.'Lennert, T. Nozaki, H. Riesekrg, A. Wagner, aad P. Warming, Proceedings of 1980 Vienna Wire - (I2alference.

22,' H.1""", R. Hamerstiom, and C. Rubbia, Nucl. Instr. andMeth. @ (19739 .

23. V. Radeka, IEEE Trans. Nucl. Sci. 21 (1974) 51. -

24. A. Breskin, G. Char@, F. Sauli, and J. Santiard, Nucl. In&r. and M&h, '119 (1974) 1.

25. V. Radeka and I?. Rehak, I= Trans. Nucl. Sci. 25 (1978) 46. -

26. V. Radeka, IEEE Trans. Nucl. Sk., Vol. NS-21, No. 1 (1974).

27. A. Dwurazny, L. Hajduk, Z. Hajduk, H. Pa%, M. Turala, E. Lorenz, R. Richter, and J. Turnau, Nucl. Instr. and Met%. 156 (1978) 245. .-

28. M. Claveti et. al., Proceedings of 1980 Vienna Wire chamber confere.nce.

29. A. Brekin, G. Charpak,' F. Sauli, and J. 61. Santiard, Nucl. I&str. and f4eth. 119' (19749 1.

30. M. Atac a& J. Urish, Nucl. Instr. and Meth. 156 (1978) 163.

31. L. Camilleri et. al., Nucl. Insti. and Meth. 156.(1978) 275.

32. D. Achterbert et. al., Nucl. Ii-&x. and Meth.'156 (1978) 287.

33. A. Bechini et. al., Nucl. Instr. aud Meth. 156 (1978).

TM-954

'Table I

NumbermdF?.ef~~m

22 H. Foeth et. al.

26 V. Radeka et. al.

Wire Resistance .em RF9 qWm !J- (cm)

10 720 0.2

240 2350 0.5-l-2

18 J. Heintze et. al. 250 300 1.6

27 A. Dwurazny et. al. 60 2000 0.6

28 M. Clavetti et. hl. 250 .1.5-2 using

'Table3 2

'Delay'Line'Characteristics

DC Resistance Delay Length %llS

29 G. charpak et. al. Wound 1300

30 M. Atac et. al. Printe.d 85 40 1.85

31 L. Ckmilleri et. al., 550 110 2.3 150 5

1.3 2-3.5

32 0. Achterberg et. al. Wound 325 22 3.66 100 4 I iz

33. A.' Bechini'et. al.' Wound 1200 580 7.43 50 2 I

-139 TM-954

Fig. 1

Fig. 2

Fig. 3

Fig. 4a and b

Fig. 5

Fig. 6

Fig. 7

Fig. 8

Fig. 9

Fig. 10

Fig. 11

'FigureCz&&icins

A typical stereo arrangement of three proportionall whe - phnes.

Nuder of multitrack ambiguities as a function of.si.rml- taneous track multiplicities.

Bi-dirmnsional. proportional wire charher with readout cathode strips.

Cathode stripreadoutarrangements forCEXL0 andT= cylindrical proprtional cdmmbers, respectively.

Resistive cathode readout bi-dimensional pmpz&ional wire chambers.

Histogramdistributionof centroidmeasuremmts using a collimated Fe55 x-ray source.

Centroid positions versus source positions.

Resistive Cathode chmber with pad readout for high rate readout capability.

Timedistributionof tracks frcmalrmancdewire spacing ofaproportiondLwirechmber.

S&mnatic description of charge division readout technique.

Multitrack resolution from Femilab delay line rmdout.

TM-954 -14-

Y

FIG. I

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20

+

+

+ + +2+ + +2+ +

5 5 -p 32 32 462 462 242 242 2 2+ 2 2+

fK4 fK4 ‘$ ‘$ 6 6

I I I I I I I I 5 5 IO IO I5 I5 20 20

NUMBER OF HITS NUMBER OF HITS

+

FIG. 2

,,,,

-lb- TM-954

FIG. 3

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TM-954

43 .

l-i bmm

\

1 ‘ Anode wires

l?C. Sttips

Rb sistive Cathoder surfaces 25 /, thick cu-strips

12Sp thick Mybc &I -Sn Oxide RrsisGve Film

Cathode ( 30 kQ/bquafa 1

FIG. 5

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I 2 3 I 5

CENTROID POSITION (mm)

FIG.6

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FIG. 7

CENTER OF GRAVITY (mm)

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I: I mm spacing

. .

. .

. .

. .

. .

. .

.

I- I-- 3mm 3mm

. *

. .

. .

. .

. .

l

.

.

.

.

.

.

.

.

charged particle

/ Roha foam

Ground

film cothode

FIG, 8

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0 25 50

RELATIVE DELAY bmc)

FIG. 9

S=2Lcd I- ---------------j 1 Ia

L --. 0 ----- --- t ----I 1

Ll Q

/ 200

QP ilWdt

0

Ll- L2

0

FIG. IO

-25-

FERMILAB DELAY-LINE DRIFT CHAMBER

TDC TDC . I A 8

tA + t; p tg+t;l zs Con%'.

brift = 2oQ “‘/cm

Y

25-

E20-

i IS- A * a IO-

5-

rerolutlon line Dead

AX (mm) AY (cm) area (cm*) I IS 1.5

2 5 I 2.5 0 0

I I I I , x I 2 3 4 5

A+& drift (mm 1

FIG. I I