PEBS Positron Electron Balloon Spectrometer SPIROC Readout in

PEBS - Positron Electron Balloon Spectrometer SPIROC Readout in PEBS Orsay, March 2009 Waclaw Karpinski I. Physikalisches Institut B RWTH Aachen

Outline • Introduction • PEBS detector concept • Description of the Prototype Board for a PEBS Sc. Fi-module with 128 channels • First measurements • Summary 2. 07. 2009 Waclaw Karpinski 2

PEBS • PEBS is a project in Research & Development phase The purpose of the experiment is a precision measurement of the electron & positron cosmic ray flux in the energy range from 1 to 2000 Ge. V. • • Superconducting magnet, B-Field: 0. 8 Tesla • • 4 Sc. Fi-Outer Tracker Planes - single Point resolution 0. 050 mm 6 Si-Inner-Tracker Planes - single Point resolution 0. 010 mm 2 TRD‘s, each with 12 layers - Proton Rejection 104 @ 100 Ge. V • 11 X 0 ECAL, Weight 650 kg • Key parameters: Acceptance: ~3000 cm 2 sr Weight: ~2000 kg Power: ~900 Watt • R&D Phase: 2006 – 2009 Construction Phase: 2010 – 2012 PEBS-1 2012 – 2014 PEBS-2 2. 07. 2009 Waclaw Karpinski 3

PEBS Collaboration Proposal for PEBS-1 & PEBS-2 submitted to NASA in March 2009 by: • Prof. J. Beatty, Ohiho State University PEBS To. F, Gondula • Prof. G. Dissertori, ETH Zuerich, Switzerland PEBS ECAL • Prof. Dr. T. Nakada, EPF Lausanne, Switzerland PEBS ECAL • Prof. Dr. S. Schael, RWTH Aachen, Germany PEBS Magnet, TRD, Tracker • Prof. Dr. S. Swordy, University Chicago, USA PEBS Trigger, DAQ, RICH • Decision expected by September 2009 4 2. 07. 2009 Waclaw Karpinski 4

PEBS is planned to be a part of NASA`s Scientific Ballooning Program Two flights : – Arctic : in 2012 – Antarctica: in 2014 Why go to Arctic or Antarctica? Because the Sun never sets during summer! And stratospheric wind pattern is circular around pole. CREAM 2004 2. 07. 2009 Waclaw Karpinski ~42 days 5

THE ELEMENTAL COMPOSITION OF HIGH ENERGY COSMIC RAYS: BALLOON PAYLOAD Solar Panel PARACHUTE HELIUM LAUNCH VEHICLE DESCENT ON PARACHUTE AT FLOAT 40 km altitude (3 mbar)

Outer-Tracker Module support: 10 mm Rohacell foam between two 100 µm thin carbon fiber skins five layers of scintillating fibers, 250 µm, glued to top and bottom of support structure 8 Si. Pm arrays on each module end Si. PM arrays: - 32 channels 0. 25 x 1. 1 mm 2 - 80 pixels/channel 256 readout channels per module-end 2. 07. 2009 250 µm Waclaw Karpinski 7

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Readout Boards • Outer Tracker: - 8 Spiroc 1 chips per board - Spirocs mounted on BGA carriers - 256 channels per board - For PEBS-1 and PEBS-2 in total 1700 Spiroc 1 chips needed • ECAL: • One Spiroc 1 chip per board • 144 boards needed 2. 07. 2009 Waclaw Karpinski 9

Prototype Board HPE-SPIROC-128 • analogue, multiplexed readout of 128 channels • 4 Spiroc chips, 32 channels per chip used • chips mounted on a pluggable chip carrier • differential analogue data transfer at 5 MHz to higher DAQ SPIROC • download of slow control parameters via USB or SPI interface Interface to higher DAQ 2. 07. 2009 Waclaw Karpinski USB Interface 13 mm SPI Interface 16 mm 10

First results • The readout board is operating satisfactory • 32 chips assembled on the chip carriers • Chip yield ~60% • some chips might have been damaged by us during commissioning of the readout board 2. 07. 2009 Waclaw Karpinski SPIROC 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Digital Part Analogue Part SR Output DACs Output ok ch 15: Vmin=VRef ok ok ok ch 0: Vmin=VRef ok ok error ok ok ok Vmin ~ 1. 1 V ok error ok broken error ok ok ---- broken ---ok ok ch 10: low gain ok ok ok ok ok error ok ok ---- broken ---error 21 channels bad ok ok error ok ok 11

Single photoelectron spectrum Aachen prototype board • Spectra taken with Aachen prototype and Orsay test board under the same conditions: o High gain, Cfb=100 f. F, T=25 ns o Hamamatsu Si. Pm S 10362 -11 -100 C o Vbias =70. 2 V, I=0, 60µA Orsay test board • good S/N ratio ~ 8 • no significant differences in gain and noise performance between the readout boards 2. 07. 2009 Waclaw Karpinski 12

SPIROC vs. VA 32_75 • • • Measurements performed with Si. Pms from Hamamatsu MPPC 5883@71 V Readout at 5 MHz multiplexing Spiroc: High Gain, Feedback Cap. =100 p. F, Shaping Time=25 ns VA 32 -75 damping 300 x on the input SPIROC much better performance Hamamatsu MPPC 5883 @ 71 V VA 32 – 75 Readout SPIROC Readout Spi. Roc S/N: 7. 9 2. 07. 2009 Waclaw Karpinski VA 32_75 S/N: 3. 3 13

Power consumption Unlike the operation in ILC, in PEBS it is not possible to use the power pulsing method to reduce the power consumption of the SPIROC chips The total power consumption amouts to~ 390 m. W/chip → 10. 8 m. W/ch Not acceptable for PEBS-Tracker ! For PEBS maximal power consumption allowed: < 2. 5 m. W/channel at multiplexer frequency of 5 MHz Breakdown of the power consumption: – preamplifier+shaper = 4 m. W/channel – SCA = 5. 6 m. W/channel – auxiliary parts (not needed in our application ) =2. 2 m. W/channel 2. 07. 2009 Waclaw Karpinski 14

Reduction of Power Consumption Turn off Preamplifier LG – Pin 222, ibi_pa_lg directly to GND Turn off Gain Selection - on pin 192, ibo_gs , directly to VDD vdda_pa : vdd_pa: 34. 0 m. A → 17. 8 m. A 6. 0 m. A → 3. 8 m. A vdd_gs: 9. 5 m. A → 9. 3 m. A → 9. 0 m. A → 7. 9 m. A - on pin 193, ibm_gs, directly to VDD - on pin 194, ibi_gs, directly to GND Turn off ADC – on pin 191, ib_adc_discri, directly to GND • vdd_adc : 4. 9 m. A → 0 m. A Reduce SCA power – pin 212 ib_SCA , 47 k. Ohm to Vdd vdd_sca: – 510 k. Ohm to GND ( 5 MHz readout ): – 68 k. Ohm to GND (1 MHz readout) : Turn on output buffer only for reading vdd_ gs: 62 m. A → 13 m. A 62 m. A → 3 m. A 7. 9 m. A → 0 m. A After reduction the total power consumption decreases to : 2. 5 m. W / channel at 1 MHz readout frequency 3. 4 m. W / channel at 5 MHz readout frequency , 2. 07. 2009 Waclaw Karpinski Still too much ! 15

Analog Output Impedance SPIROC does not have a high impedance analog output unlike the digital outputs, the analog outputs cannot be directly connected in a daisy chain 2. 07. 2009 Waclaw Karpinski 16

Summary So far the optimal chip does not exist. Two options: SPIROC VA 64 from Gamma Medica-Ideas Spiroc show better performance SPIROC has an excellent S/N performance The DAC operates very well The power consumption however is too high 2. 07. 2009 Waclaw Karpinski 17

Summary Requirements for the new SPIROC optimized for PEBS – 64 channels (32 channels version not excluded) – analogue functionality only – Power consumption < 2. 5 m. V channels – Additional power shut down for following stages : • preamp low gain • preamp high gain • gain selection • SCA – Daisy chain of analogue outputs – Differential current output which is turned on for reading only Quantity: ~ 1000 chips with 64 channels 2. 07. 2009 Waclaw Karpinski 18