A modular data acquisition system for multiware proportional chambers

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A M 0 D U L A R D A 7 A A C Q U 1 5 1 7 1 0 N 5 Y 5 7 E M F 0 R MUL71W1RE PR0P0R710NAL CHAM8ER5 M. C A V A L L 1 - 5 F 0 R 2 A

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J05eph Henry La60rat0r1e5, Pr1ncet0n Un1ver51ty, Pr1ncet0n, N.J., U.5.A. Rece1ved 23 March 1973 We de5cr16e a 51mp1e M W P C e1ectr0n1c5 5y5tem, 1n wh1ch m05t 0f the e1ectr0n1c5 15 m0unted 0n the cham6er5. 7 h e 5y5tem u5e5 1atche5 f0r temp0rary pu15e 5t0ra9e and 0ffer5 6uffer1n9 0pt10n5 f0r data tran5fer t0 c0mputer and tape. 1t ha5 6een 1n u5e f0r 0ne

year 1n an 1nten5e pr0t0n 6eam at the A1ternat1n9 6rad1ent 5ynchr0tr0n 0f 8r00khaven Nat10na1 La60rat0ry, 5erv1n9 a t0ta1 0f 3100 w1re5.

1. 1ntr0duct10n

character15t1c5 0f the5e cham6er5. We have taken the a1ternat1ve v1ew that even a 51mp1e 5y5tem can 5erve the need5 0f m05t exper1ment5, 50 that 0ne can decrea5e the c05t and c0mp1ex1ty 0f the M W P C 5y5tem 6y 5acr1f1c1n9 50me de9ree 0f ver5at111ty. We rev1ew 6r1ef1y the type5 0f 1091c 1n u5e (1nc1ud1n9 0ur 0wn) t0 p01nt 0ut what are the1r ma1n character-

A num6er 0f e1ectr0n1c 5y5tem5 have 6een deve10ped f0r the read0ut 0f mu1t1w1re pr0p0rt10na1 cham6er5; m05t 0f them are de519ned t0 u5e fu11y the de51dera61e * Pre5ent addre55: Department 0f Phy51c5, Harvard Un1ver51ty, Cam6r1d9e, Ma55., U.5.A.

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M. C A V A L L 1 - 5 F 0 R 2 A

15t1c5, advanta9e5 and draw6ack5. 7here are three c0mm0n type5 0f 1091c, wh1ch d1ffer 1n the way a MWPC pu15e 15 5t0red, wh11e wa1t1n9 f0r a fa5t 1091c dec1510n 0n acceptance 0r reject10n 0f an event. (1) De1ay ca61e 5t0rat7eL), 5ee f19. 1a. 7he 519na1 pu15e 15 d15cr1m1nated and c0nverted t0 a narr0w pu15e, wh1ch 15 then de1ayed 6y a f1xed 1en9th 0f ca61e. 1f the fa5t 1091c accept5 the event, the de1ayed pu15e 15 5tr06ed 1nt0 a 1atch. 7h15 5y5tem reduce5 t0 a m1n1mum the 51n91ew1re dead t1me, wh11e 0ffer1n9 the m05t 5ta61e and accurate de1ay. 1t a150 av01d5 any 5y5tem dead t1me f0r the reject10n 0f event5; thu5, 1t fu11y ut1112e5 the h19h rate capa6111t1e5 0f MWPC•5 w1th0ut de9rad1n9 the1r t1me re501ut10n. 7he draw6ack5 0f th15 5cheme are c05t and c0mp1ex1ty due t0 ca611n9, p1u5 1ack 0f f1ex16111ty 1n the t1me a110wed f0r fa5t 1091c dec1510n5, wh1ch 15 f1xed 6y the 1en9th 0f de1ay ca61e5. (11) 0ne-5h0t 5t0ra9e2), 5ee f1y. 16. 7he 519na1 pu15e 15 d15cr1m1nated and c0nverted t0 a pu15e 0f prec15e1y determ1ned 1en9th. 1f the event 15 accepted, the c11pped tra111n9 ed9e 0f the d15cr1m1nated pu15e 15 5tr06ed 1nt0

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a 1atch. 7he t1me a110wed f0r the fa5t 1091c dec1510n 15 f1xed 6y the 1en9th ch05en f0r the d15cr1m1nated pu15e. 7he pu15e 1en9th mu5t 6e accurate 50 a5 n0t t0 de9rade the 1ntr1n51c re501v1n9 t1me 0f the cham6er, and th15 d1ctate5 50me extra 50ph15t1cat10n 0f the e1ectr0n1c53). 0 n the 0ther hand, th15 5cheme a110w5 hav1n9 part 0f the read0ut 1091c 0n the cham6er. 7he ca611n9 15 thu5 reduced 6ecau5e the 0utput5 can 6e enc0ded 519na15 rather than 1nd1v1dua1 w1re 519na15. (111) Latch 5t0ra9e4), 5ee f19. 1c. 7he d15cr1m1nated pu15e pa55e5 thr0u9h a n0rma11y 0pen 9ate and 5et5 a 1atch 6ef0re any fa5t 1091c dec1510n 15 made. A fa5t 0 R 0f a11 w1re5 1n a cham6er 5hut5 the 9ate after a de1ay; 1atche5 are pr0mp1y re5et and 9ate5 are re0pened 1f the event 15 rejected. 7he ma1n draw6ack 0f th15 5y5tem 15 that 1t 1ntr0duce5 a 5y5tem dead t1me f0r every pu15e 1n any cham6er. 0 n the 0ther hand 1t ha5 5evera1 advanta9e5 that eventua11y 1ed u5 t0 ch005e 1t: a) 7he 1atch 5t0ra9e a110w5 c0mp1ete f1ex16111ty1n the fa5t 1091c dec1510n t1me. 6) 0n1y the 51mp1e5t d15cr1m1nat10n 15 needed 6ecau5e ~ - M C 10 10 ~

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F19. 2 . 5 c h e m a t 1 c 5 0 f the Amp11f1er-D15cr1m1nat0r-6ate ( A D 6 )

L061C

a n d L a t c h (L) card5.

83

A M 0 D U L A R D A 7 A A C Q U 1 5 1 7 1 0 N 5Y57EM

a11 t1m1n9 1nf0rmat10n 15 c0nta1ned 1n the 1ead1n9 ed9e 0f the d15cr1m1nated pu15e. c) 8ecau5e 0f the reduct10n 1n c0mp1ex1ty 0f the 1nput c1rcu1try, a 900d p0rt10n 0f the read0ut 1091c can 6e m0unted 0n the cham6er, thu5 reduc1n9 ca611n9 t0 a m1n1mum. 7he dead t1me 11m1tat10n c0u1d 6e c1rcumvented, 1n exper1ment5 where 50me cham6er5 51t 1n the 6eam, 6y u51n9 a ••hy6r1d•• 5y5tem: the w1re5 1n the 6eam w0u1d 6e 5erved 6y e1ectr0n1c5 0f type (1) 0r (11). 7h15 w0u1d e11m1nate the maj0r 50urce 0f dead t1me, at the pr1ce 0f a 5119ht 1ncrea5e 1n 1091c c0mp1ex1ty. 2. De5cr1pt10n 0f the e1ectr0n1c5: F1r5t 5ta9e5 7he f1r5t 5ta9e5 0f the e1ectr0n1c5 u5e MECL [[ 1nte9rated c1rcu1t55). 7hey are 6u11t 1n m0du1e5 c0mp05ed 0f tw0 c0up1ed pr1nted c1rcu1t card5: Amp11f1erD15cr1m1nat0r-6ate (AD6) card and Latch (L) card, that are m0unted d1rect1y 0n the cham6er56). Each m0du1e pr0ce55e5 519na15 fr0m 14 w1re5. Amp11f1cat10n, d15cr1m1nat10n and 9at1n9 are perf0rmed f0r each w1re 6y the 3 d1fferent1a1 amp11f1er5 1n an MC1035 1nte9rated c1rcu1t (5ee f19. 2). 7he 1nput 5ta9e

7A8LE 1 Ma1n parameter5 0f the amp11f1er-d15Cr1m1nat0r. (1) 7hre5h01d v01ta9e f0r ne9at1ve pu15e5, V71~ (2) Max1mum channe1-t0-channe1 var1at10n 0f V2~ (50 5amp1e5) (3) Var1at10n 0f V7H w1th P.5. v01ta9e VEE, f0r V~E = - 5.2 V (4) 7emperature dependence 0f V7H (5) 7emperature 5ta6111ty ran9e (6) 7hre5h01d v01ta9e f0r p051t1ve pu15e5 (7) 51ew1n9 10 mV~< V1nput<~50mV V1nput~>50 mV (8) Pu15e w1dth, v (9) Av due t0 channe1-t0-channe1 var1at10n (10) Av due t0 pu15e he19ht var1at10n (11) Rec0very t1me (12) Cr055ta1k 1mmun1ty 0n pr1nted c1rcu1t 60ard

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15 a X6, 51n91e ended 1nvert1n9 amp11f1er. 7he 5ec0nd d1fferent1a1 amp11f1er 15 turned 1nt0 a d15cr1m1nat0r 6y pr0v1d1n9 the dc 0ff5et w1th a re515t1ve cha1n and the ac p051t1ve feed6ack w1th a capac1t0r. 7he d10de 15added

AD5-Card (5e, F19.2) L - Cetd

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5tart Re5et t0 fr0m C0mputer C0mputer F19. 3. 0perat10n 0f the L0ca1 L091c and Fa5t L091c.

84

M. CAVALL1-5F0R2A AND D. C. CHEN6

f0r temperature 5ta61112at10n and fa5ter rec0very t1me. 7he th1rd 5ta9e pr0v1de5 9at1n9 6y u51n9 5h1fted 1091c 1eve15 f0r the ena611n9 1nput. A 1eve1 1n the m1dd1e 0f the tran5fer curve ( - 1 . 2 V) a110w5 the 519na1 at the 0ther 1nput t0 6e pr0pa9ated thr0u9h the 9ate, a 1eve1 ( - 2 . 0 V ) 10wer than the MECL 1091ca1 2er0 1eve1 ( - 1.6 V) 610ck5 1t. 7he ma1n parameter5 0f the amp11f1er-d15cr1m1nat0r are 91ven 1n ta61e 1. 7h15 c1rcu1t d1ffer5 fr0m many 0ther5 a1ready pu6115hed 1n 1t5 rather h19h (10 mV) thre5h01d v01ta9e. A1th0u9h the deta11ed perf0rmance 0f pr0p0rt10na1 cham6er5 u51n9 th15 e1ectr0n1c5 5y5tem 15 de5cr16ed 1n the f0110w1n9 paper7), we can 5tate here a c0nc1u510n 0f that paper: we d1d n0t enc0unter any d1ff1cu1ty 1n 0perat1n9 the cham6er5 at fu11 eff1c1ency.

c105e5 a11 the 9ate5 0f the cham6er 0n the AD6-card5. 7he t1me 6etween the 1ead1n9 ed9e 0f the cham6er pu15e and the c1051n9 0f the 9ate 15 the re501v1n9 t1me 0f the cham6er. 1t can 6e adju5ted fr0m a m1n1mum 0f 50 n5 6y the u5e 0f de1ay ca61e. 7he 9at1n9 c1rcu1try 15 acc0m0dated 0n a ••L0ca1 L091c•• 60ard, 50 ca11ed 6ecau5e 1t 15 p051t10ned near the cham6er 1t 5erve5. 7he Fa5t L091c can dec1de t0 accept 0r reject an event. 1n the f0rmer ca5e, the read0ut 0f 1atche5 and the data ac4u151t10n 6y the c0mputer are tr199ered, wh11e the 9ate 1atche5 0f the cham6er5 are kept c105ed. [n the 1atter ca5e, the fa5t 1091c f1r5t re5et5 a11 L-card 1atche5 and then re5et5 the 9ate 1atch 0f the cham6er5, thu5 6e91nn1n9 a new cyc1e. 7he fa5t 1091c dec1510n 15 made (5ee f19. 3) 6y re4u1r1n9 a c01nc1dence fr0m a 5e1ected c0m61nat10n 0f cham6er5 and 5c1nt111at10n c0unter5. 7he 0 R 0f a11 cham6er5, after a de1ay, 9enerate5 a reject 1f the c01nc1dence c0nd1t10n ha5 n0t 6een ver1f1ed. 7he 0 R 0f a11 cham6er5 a150 c105e5 the 9ate 1atche5 0f cham6er5 that are n0t re4u1red 1n the event-def1n1n9 c01nc1dence, t0 av01d 1ater unc0rre1ated pu15e5 1n them 1f a pu15e ha5 n0t 5hut the 9ate 1atch at the t1me 0f the event.

3. 5 y 5 t e m 0perat10n

Dur1n9 0perat10n, the 9ate5 0f a11 w1re5 are 0pen unt11 a w1re f1re5.7he d15cr1m1nated pu15e 90e5 thr0u9h the 9ate and 5et5 the c0rre5p0nd1n9 R5 f11p-f10p 0n the L-card (f19.2). 1t 15 a150 0R•ed t0 a11 0ther w1re5 0n the 5ame card t0 pr0duce a card 0 R . 7he 0 R 0f a11 card5 1n a cham6er 5et5 the " 6 a t e Latch•• that, after a de1ay,

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A M 0 D U L A R D A 7 A ACQU151710N 5Y57EM

4. Read0ut A5 0f t0day, f0r a11 5y5tem5 1n wh1ch the data fr0m exper1menta1 apparatu5 are eventua11y 5t0red 0n ma9net1c tape, the 0vera11 11m1t 0n data ac4u151t10n rate 15 5et 6y the tape wr1t1n9 5peed. 7he 1atter, typ1ca11y 0f the 0rder 0f a few m5/event (3 m5/event 1n 0ur ca5e), nu111f1e5 the 9a1n5 that a very fa5t and 50ph15t1cated read0ut 5y5tem can 91ve; 1t ar9ue5, h0wever, 1n fav0r 0f 6uffer1n9 the 1nf0rmat10n 0n the way t0 the c0mputer, 1n 0rder t0 have the apparatu5 • a11ve•• wh11e an event 15 6e1n9 tran5ferred t0 the c0mputer 0r t0 tape. F0r the5e rea50n5 we have 6u11t a 51mp1e and m0derate1y fa5t read0ut 5y5tem, that 91ve5 the 6uffer1n9 0pt10n. 7he L-card 1atche5 are 5canned 5er1a11y, w1th each cham6er read 0ut 6y 1t5 0wn m0du1e, the "Reader••,

85

5h0Wn 1n f19. 4. 7he addre55e5 0f the W1re5 that f1red are dep051ted 1nt0 5h1ft re915ter5, Wh05e C0ntent5 are read 1n f1Xed f0rmat 6y an HP 2114 C0mpUter; the Cham6er5 are reC09n12ed 6y the 0rder 0f the W0rd read 1n. 7he Reader e1ectr0n1C5 15 6U11t W1th 7 7 L 1nte9rated C1rCU1t5. A 9ated C10Ck, tr199ered 6y the fa5t 1091C, 1nCrement5 a 9-61t 61nary C0Unter U5ed a5 a 5e4Uent1a1 addre55 9enerat0r. 7he 4 1ea5t 519n1f1Cant 61t5 addre55 the data 5e1eCt0r5 0n the L-Card5 (f195. 2 and 4), Wh11e the 5 m05t 519n1f1Cant 61t5, thr0u9h a 5-61t-t0-32-11ne5 deC0der, ena61e 5e4uent1a11y each L-Card Up t0 a t0ta1 0f 32. 1f a 1atCh 0n an L-Card 15 5et, 1t W111 0UtpUt a 519na1 0n a C0mm0n ••h1t•• 11ne When addre55ed 6y the 61nary C0Unter. 7he ••h1t•• 519na1 W111C10Ck 1nt0 9 5h1ft re915ter5 the 0UtpUt5 0f the 9-61t 61nary C0Unter; th15

F19. 5.8ack v1ew 0f a 5ma11cham6er (28 519na1 w1re5) c0nnected t0 2 AD6-L-card5.7he 1ar9e pr1nted c1rcu1t 0n t0p enc105e5 the 10ca1 1091c and the reader.

86

M. C A V A L L 1 - 5 F 0 R 2 A AND D. C. C H E N 6

num6er c0rre5p0nd5 t0 the addre55 0f the w1re that f1red. 1f there are m0re h1t 519na15 than 5h1ft re915ter 10cat10n5, a 51mp1e 0R1n9 c1rcu1t (n0t 5h0wn 1n f19. 4) 5et5 an 0verf10w 61t. 7he read0ut rate 15 11m1ted 6y the re4u1rement that the 61nary c0unter ha5 n0t yet chan9ed 5tate when the h1t 519na1 arr1ve5 at the 5h1ft re915ter5. 7he h19he5t c10ck rate that 5at15f1e5th15 re4u1rement 15 6 MH2; we have 0perated at a c0n5ervat1ve 3.3 MH2, re5u1t1n9 1n a t0ta1 read0ut t1me 0f a60ut 150 p5 f0r a 32 A D 6 - L card cham6er. 0nce an event 15 read 1nt0 the 5h1ft re915ter5, the 1nput 9ate5 can 6e re0pened and an0ther event can 6e dep051ted 1n the L-card 1atche5, wh11e the f1r5t event 15 read 1nt0 the c0mputer.

1t 15 a p1ea5ure t0 ackn0w1ed9e the c0ntr16ut10n 0f 6 . K. 0•Ne111, f0r the f1r5t ver510n 0f the amp11f1erd15cr1m1nat0r c1rcu1t and f0r a5515t1n9 u5 w1th many 1dea5 and 5u99e5t10n5. W. W. A5h, D. 6 . C0yne, 6 . 60991 and D. 6r055man a150 c0ntr16uted much t0 th15 5y5tem. We a150 w15h t0 thank W. Wer05ta and R. App1e f0r the1r techn1ca1 he1p, and K. Wr19ht and 8. 61665 f0r the1r c00rd1nat1n9 eff0rt and the1r many he1pfu1 5u99e5t10n5. 1n part1cu1ar, we are 9ratefu1 t0 M. 80w16y and A. Kara9051an, w1th0ut wh05e 5k111 we c0u1d n0t have 6u11t 0ur 5y5tem 1n 5uch a 5h0rt t1me. 0 n e 0f u5 (M.C.-5.) w0u1d 11ke t0 thank A. 61911 8er201ar1 w1th0ut wh05e enc0ura9ement and 5upp0rt 1t w0u1d n0t have 6een p055161e f0r h1m t0 part1c1pate t0 the w0rk rep0rted.

5. Lay0ut, ca611n9 and c05t c0n51derat10n5 F19. 5 111u5trate5 an examp1e 0f th15 5y5tem: a 5ma11 cham6er ( 4 x 4 1nch aperture, 28 519na1 w1re5) w1th 2 AD6-L-card5, ca61ed t0 the 10ca1 1091c and reader. 7he tw0 1atter un1t5 are acc0m0dated 0n 0ne pr1nted c1rcu1t 60ard 6ecau5e 0f the 51mp11f1cat10n 0f ca611n9 that th15 a110w5. N0te a150 that the AD6-L-card5 are m0unted 1n the cham6er p1ane, t0 a110w 5tack1n9 0f cham6er5. 7he f1at r1660n ca61e 8) 5h0wn 1n f19. 5 are u5ed 1n the a1ternate 9r0und c0nf19urat10n, that 91ve5 1.5 n5/f00t pr0pa9at10n de1ay and 100 f2 character15t1c 1mpedance. Ca61e5 0f the 5ame k1nd are u5ed f0r the fa5t 1091c and c0mputer 1nterface c0nnect10n5. 1t can 6e 5een fr0m f195. 3 and 4 that m05t 0f the 519na1 11ne5 are da15ycha1ned t0 reduce ca611n9 t0 a m1n1mum. 7he maj0r p0rt10n 0f the 5y5tem 15 1n the A D 6 - L m0du1e5. 7he un1t c05t 0f the5e (1nc1ud1n9 a11 hardware and a55em61y) am0unt5 t0 $5.90 per w1re. 7he t0ta1 c05t 0f the e1ectr0n1c5 per w1re, ( A D 6 - L , 10ca1 1091c, reader m0du1e5 p1u5 a11 ca611n9 up t0 the c0mputer 1nterface) 15 a60ut $7.00.

Reference5 1) 5ee f0r examp1e: H. Cun1t2, J. D1eper1nk and W. 51ppach, Nuc1.1n5tr. and Meth. 91 (1971) 211 ; E. 8100m, R. L. A. C0ttre11, 6 . J0hn50n, C. Pre5c0tt, R. 51emann and 5.5te1n, Nuc1. 1n5tr. and Meth. 99 (1972) 255. 2) 5ee f0r examp1e: J. C. 7ar16 and H. Verwe1j, Nuc1. 1n5tr. and Meth. 78 (1970) 93; J. C. 5ant1ard and F. 5au11, CERN NP 1nterna1 Rep0rt 71-2 (1971) unpu6115hed; E. R. Mart1n and D. F. J0ne5, Nuc1.1n5tr. and Meth. 98 (1972) 541. 3) 7he pu15e j1tter pr061em can 6e rather 5er10u5 0n certa1n app11cat10n5 6ecau5e any d15cr1m1nated 519na1 w1th a pu15e w1dth 0ut51de the ran9e 0f the 5tr06e w0u1d n0t 6e 5t0red. 4) 7h15 5cheme ha5 a150 6een c0n51dered 6y R. Pa965, Nuc1.1n5tr. and Meth. 85 0970) 211. ~) M0t0r01a 5em1c0nduct0r5 pr0duct5, 1nc. 6) An ear11er ver510n 0f the amp11f1er-d15cr1m1nat0r c1rcu1t ha5 6een de5cr16ed 6y 6 . K. 0•Ne111, CERN NP 1nterna1 Rep0rt 70-21 (1970) unpu6115hed.

7) M. Cava111-5f0r2a, 6 . 60991, W. W. A5h, D. C. Chen9, 8)

D. 6 . C0yne and 6 . K. 0•Ne111, Nuc1. 1n5tr. and Meth. 113 (1973) 87. ••5c0tchf1ex" f1at r1660n ca61e5, manufactured 6y 3M C0mpany.