Tript testing progress report modifications to test setup

Trip-t testing progress report modifications to test setup - hardware and software Si. PM pulse height spectra linearity measurements discriminator measurements Mark Raymond - m. raymond@imperial. ac. uk - 16/11/05

Test set-up Lab. VIEW VME Programmable Digital Pattern Generator prog. attenuator ADC now integrated into system – software written to perform automated linearity measurements (using prog. attenuator) and get Si. PM pulse height spectra ck and trig. ADC ~12 control lines preamp int. /reset pipeline, multiplexer, programming level shift d. ECL -> 2. 5 V CMOS Qinj Trip-t Mark Raymond - m. raymond@imperial. ac. uk - 16/11/05 Scope

Si. PM connection method Vbias trip-t 3 p 3 1 MW thin coax 50 W LED 82 p Si. PM would need to feed in small current here to tune Vbias for individual Si. PM’s short length (~15 cm) coax between Si. PM and tript (at the moment) Si. PM connected between core and coax sheath (core carries bias voltage) 50 W provides some kind of termination for the cable charge split between two tript channels using different capacitor values to get high/low gain Mark Raymond - m. raymond@imperial. ac. uk - 16/11/05

Si. PM/tript results single p. e. spectra (200, 000 events) Russian Si. PM (CPTA – 600 pixels) led pulsed (20 ns) during preamp integrate period (red distribution) preamp integrate: reset ratio 350 ns: 50 ns get blue distribution when led switched off (~ 1 or 2 p. e. ) Mark Raymond - m. raymond@imperial. ac. uk - 16/11/05

Si. PM/tript results – signal vs led pulse amplitude single p. e. spectrum visible increasing led pulse amplitude limit of high chan. linear range (~ 2 p. C in this case) high gain channel each distribution shows the spectrum obtained for a fixed led pulse amplitude led saturating? low gain channel expand Mark Raymond - m. raymond@imperial. ac. uk - 16/11/05 ~ 25 p. C

linearity studies test charge injected via programmable attenuator ~ 2 p. C different curves for different values of tript discriminator threshold voltage Vth. high gain channel linearity not expected to be that good for this version of the chip (see Fermilab tript test docs. ) ~ linear range discontinuities occur at different points depending on programmed disc. threshold setting low gain channel discontinuities occur where signal crosses Vth - could be due to crosstalk on chip or test board needs further study – may need careful strategy to calibrate out in system Mark Raymond - m. raymond@imperial. ac. uk - 16/11/05

discriminator timing studies – early result charge injection edge tript discriminator output td discriminators outputs constantly enabled so appear immediately at chip O/P when they fire measure td (scope)for many triggers for different signal sizes note: td also includes fixed cable delays Mark Raymond - m. raymond@imperial. ac. uk - 16/11/05

discriminator timing studies – early result Qin~600 f. C distributions show value of td (delay between charge injection edge and disc. firing) for different values of charge, but for fixed value of discriminator threshold setting Qin~100 f. C take distribution mean values and plot dependence on Qin points to note: charge injection edge also contributes here (~ 5 nsec => should deconvolve out) actual disc. threshold value (~ 100 f. C here) in our system will depend on: programmed Vth value programmed tript gain Si. PM gain external gain ratio capacitors => many more careful and systematic measurements required here Mark Raymond - m. raymond@imperial. ac. uk - 16/11/05 this plot shows timewalk dependence on signal size

summary tript results with Si. PM encouraging single p. e. spectra visible and charge splitting to get high/low gain channels works linearity shows results consistent with previous chip measurements discontinuities occuring when discriminators fire need further study – try to reduce and/or understand how to manage in system discriminator timing studies begun – more systematic study needed our next priority investigate performance dependence on connection cable length between Si. PM and tript look for degradation with cable length (noise, timing performance) – important to understand from detector design perspective (how far can front end boards be from Si. PM’s) propose to try and do this with scintillator/wavelength shifting fibre -> Si. PM system using cosmics and external scintillator trigger system to get reference timestamp to compare with Si. PM/tript value system currently under construction Mark Raymond - m. raymond@imperial. ac. uk - 16/11/05

Photos Trip-t (1 st version) charge injection split between 2 adjacent channels 2. 5 V CMOS control lines Mark Raymond - m. raymond@imperial. ac. uk - 16/11/05

Photos Trip-t board d. ECL -> 2. 5 V CMOS level shift ADC digital pattern generator d. ECL outputs Mark Raymond - m. raymond@imperial. ac. uk - 16/11/05