1. Ideas on VFEE I. Durán Universidad de Santiago de Compostela NUSTAR Calorimeter WG Valencia, June 2005

2. Preliminars Valencia 2005  The crystal response is dramatically dependent on the readout procedure APDs have been adopted by CMS(ECAL), ALICE(PHOS) etc CsI(Tl)+APDs  Starting solution Hamamatsu S8148 5x5 mm 2  40€/unit

3. APDs vs PMTs Valencia 2005  APDs size: smaller price: cheaper Q.E: better Gain: lower H.V: 300-400 V < 1  A Same resolution Very low power ~ 0.2 mW

4. Electronic chain Valencia 2005 Mass storage ASIC/VLSI Low power Digitizer (?) HELP!!! Trigger Logic Transimpedance Preamplifier  PICA (Bo Jakobson et al)  MATE (IPNO) ? ...... ?

5. p’s and  ’s Valencia 2005  If p and  have to be measured simultaneously two APD channels with different gain are needed

6. Valencia 2005 Gain dependence on T and V APD Gain  Crystal’s response depends on T  T must be kept very stable ! ~0.1 o otherwise, T should be accurately measured in order to keep gain constant by controlling the bias voltage

7. T screening Valencia 2005 Crystals VFEE Layer Liquid cooling screen 1. Overall T stabilization ~ - (10+-1) o C 2. Local T measurement 3. Gain stabilization by V regulation  Power per channel (~ 5000 ch for R3B): APD < 1mW Preampli ~ 100mW Digitizer 1W ??

8. Conclusions Valencia 2005  R & D on (crystals + readout) is needed: - USC plans to perform tests with CsI(Tl) + APD (close to real size) - Lund/Dubna have carried out tests and will continue with this task (CsI) B. Jakobsson document - Others (Call for volonteers)....