Ti m i ng Count er st at us @ Sep t. 2004 1
Ti m i n g Cou n t er act i vi t i es Ti m i n g r esol u t i on : 100 p s FWHM h ave b een ach i eved. PM s ch ar act er ised i n t h e COBRA m ag n et f or g ai n an d t i m i n g. Fu l l ch ar act er i sat i on of si n g l e TC s cou n t er i s st ar t ed Fi n al d esi g n an d i n t eg r at i on w i t h DC i s st ar t ed Ф- d et ect or : APD d i r ect l y f r om Ham am at su 2
Ti m i ng r esol ut i on m easur em ent s First test(psi- π E5)- y 03: Low Thr. - BC404 (1X5x80 cm ) l i g h t g u i d es an d 1 1/ 2 an d 2 Ham am at su Fi n e Mesh PMs - p assi ve b eam col l i m at i on (6m m d i am et er ) - 5 cm p osi t r on p at h l en g t h. - An al og i c el ect r on i cs - Dou b l e Th r esh ol d Di scr i m i n at or MCA 3 2.35x σ[ (t L- t R)]/ 2= 124 ps FWHM High Thr. Delay coinc Sci nt i ll at or PM (t L- t R) 248 ps FWHM Li g ht g ui d e 3
m aem ent s Ti m i ng r esol ut ion m easur Last test (LNF- Frascati- Beam Test Facility) January 04: En er g y Ran g e 25-800 MeV e- 25-550 MeV e+ Max. Rep et i t i on Rat e 50 Hz Pu l se Du r at i on 1-10 n s Cu r r en t / p u l se 1 t o 10 10 p ar t i cl es (Al l ow ed Cu r r en t 10 3 p ar t i cl es/ secon d ) Beam sp ot : σ x= 2m m σ y= 4m m (i n t h e f ocu s) Fur t her g eom et r i cal sel ect i on of 5m m x5m m sp ot b y t w o sci nt i ll at i ng f i b er s w i t h APD r ead - out. Ti m e sp r ead d ue t o t he sp ot si ze ~ 25p s. Coi nci d en ce w i t h APD cr oss and t he LINAC t r i g g er al low t o r ej ect m ost of t he b ck. Event s. APD Sp ot Si ze Sci nt. Fi b er Ti m e sp r ead ~ 25p s b eam APD 4
Ti m i ng r esolu t ion m easur em ent s 1. 1,2,3 el ect r on even t s ar e r esol ved i n t h e ch ar g e sp ect r u m 2. (t L- t R) i s sel ect ed i n t h e 1e p eak Ou r Best Resu l t s : 2.35x σ [ (t L- t R)]/ 2= 104±2ps FWHM 1e 2e 3e 5
Ch ar act er i sat i on i n Mag Fi el d 6
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Gai n vs Rat e Zer o f i eld 1.05 T 27.5º Th e Gai n vs Rat e at 1500 V i n zer o f i el d i s f u l l y r ecover ed at 1.05 T an d 27.5º at 2100 V. Un al l ow ab l e i n cr ease of b i asi n g vol t ag e ar e n eed ed at 0º. 9
Gai n Vs Bi as at sever al an g l es + 10º Max g ai n cu r ve i n m ag n. f i el d Sam e g ai n + 10º 10
RMS t i m i n g r esol u t i on vs p.e. at t en u at or 60p s p u l sed b l u e Laser 100u m Fi b er Laser b eam i l l u m i n at es t h e w h ol e p h ot ocat od e PM 11
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Exp ect ed Red uct i o n f act or Ext. PM Int. PM Gai n 12 @ 8.5º 5 @ 20º 35 @ 10º 15 @ 20º TTS 1.2* @ 8.5º 1.2* @ 20º 1.8* @ 10º 1.6* @ 20º Increase Positron Path- Length ~ 5 cm Improve Geom. Matching Scint.- PMT Tilt the PM @ ~ 30º respect Magn. Field Rotated Scint. Slab improves response uniformity and timing perfornce due to coincidences. 13
TC k ey f eat ur es PM active diameter Scintillator Cross Section 39x39 mm 70º PM section Fr om COBRA cen t er 105 cm 25 cm 8.5º 30º B 0.75 T 30º 10º B 1.05 T 14
Conclusions: 2 PMs allow to obtain the target resolution At first order, the resolution is limited by the number of photoelectrons (light output from scintillator, quantum efficiency of PM, coupling scintillator- PM[2 ], which has 39 mm dia. active area) At second order, the slew rate could be used to improve the resolution in sll signal regime: we have demonstrated that amplification recovers the timing resolution. 2 PMs can supply 100uA - ximum- current ( 10uA for 1.5 PMs) 2 PMs lifetime correspond to 2.3 years at the event rate of 50kHz @ gain of 6x10 5. An increase of a factor 2 can be easily obtained. To be done: - First systetic tests of single element of TC started in the run (May, 31 June, 12) and will continue in the Frascati BTF Finalize the design of TC and integration with DC 50x39 mm 39x39 mm 15
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Si ng l e Count er Resp onse St ud y 17
Ti m e Resol u t i on FWHM (p s) Si ng l e Count er Resp onse St ud y BC408 Ver y Pr el i m i nar y BC404 39x39 sl ab i n r ot at ed con f i g u r at i on si m u l at i n g a p osi t r on t r aj ect or y @ 40.5 al on g z an d 70 i n r ad i al p l an e Posi t i on (m m ) 18
Mechani cal d esi g n 19
Fr om COBRA cen t er 30 º 105 cm B 8.5 º 10 º 25 cm 30 º B 20
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3D vi ew of TC 22
Tr an sver se Ti m i n g Cou n t er 23
Cur ved d et ect or (t r i gger i ng ) The d esi gn of t he cur ved d et ect or s has b een m od i f i ed i n or d er t o m at ch t he b u d get l i m i t s f or p r ocur em ent of vi r gi n APD f or m Ham am at su (159 Eur o/ each). ~ 80 scin t i l l at i ng f i b er s an d 160 APD p er each TC. Pr ocur em ent p r el i m i nar y p r oced ur e st ar t ed APD Sci nt. Fib er s 5 x 10 m m 24
Ti m i n g Cou n t er Sch ed ul e 2002 2003 PMT Evalu at ion 2004 Beam Test 2005 PMT pr ocur. APD Eval u at ion APD pr ocu r. APD t est Design Pr ocu r & Manu f. Assem bly PMT Evalu at ion Beam Test COBRA Test PMT pr ocu r. New APDs APD Evalu at ion APD pr ocu r. APD t est APD pr ocu r. Design Pr ocu r & Manu f. Mech an i cal m at ch i n g Design Manuf act or ing Assem bl y Test Mi l est on e BG t est Ful l i n st al l at i on 25
Ф d et ect or (t r i g g er i n g ) We f ound g ood APDs w i t h hi g h S/ N r at i o t hat w e t est ed at PSI and LNF (Fr ascat i ) e- π b eam Pu r e e- b eam 26
Ф d et ect or (t r i gg er i ng ) Bu t, on l y ab ou t 10% of t h e sel ect ed APDs ar e g ood en ou g h Hu g e sp r ead i n d yn am i c p ar am et er s n ot p r ed i ct ab l e f r om st at i c p ar am et er s [l ef t f i g u r e] Th e CMS sel ect i on an d con d i t i on i n g of t h e f i r st b at ch of APDs i s n ot ap p l i cab l e t o MEG (w e ar e w or k i n g at f ew Vol t s f r om Vb k d h i g h g ai n an d w e ar e i n t er est ed t o h i g h sl ew r at e an d h i g h S/ N f or t i m i n g p u r p ose) For com p ar i son n ew APDs f r om Ham am at su h ave si m i l ar r esp on se[r i g h t f i g u r e] Mor e w or k i s n eed ed t o b et t er u n d er st an d t h e cor r el at i on b et w een st at i c an d d yn am i c p ar am et er s of CMS APDs. f r om CMS sel ect i on Fr om Ham am at su 27
St at us of t est and p r ocur em ent s of APD APD Cop p er b l ock Sp l i t t er s Pu l sed Laser APD t est b ench i n Genoa Pel t i er Cel l Int eg r at in g Cali b r at ed Ph ot om et er 1/ 1000 at t en u at or 30.00 Fast Ph ot od i od e peak-to-noise ratio @ 250 photons signal Ph ot om u lt i p l i er 20.00 Ab out 10% can b e accep t ed S/N ratio 10.00 0.00 1 11 21 31 41 51 61 71 81 91 28