Monolithic Thin Pixel Upgrade Testing Update. Gary S. Varner, Marlon Barbero and Fang Fang UH Belle Meeting, April 16 th 2004

Transcription

1 Monolithic Thin Pixel Upgrade Testing Update Gary S. Varner, Marlon Barbero and Fang Fang UH Belle Meeting, April 16 th 2004

2 Basic Technology: Standard CMOS CMOS Camera Because of large Capacitance, need Thick DSSDs -- APS can be VERY Thin Particle Detector Standard CMOS: Low Power Excellent Transistors Tight Process Control Excellent Uniformity High volume, low cost Large ADC, DSP base Key Features: q collection via thermal diffusion (no HV) NO bump bonding System on Chip possible 1

3 Continuous Acquisition Pixel (CAP) Standard APS pixel Conceptually Simple Analog reset, take sample frame and then difference Continuous Correlated Double Sampling Row-wise analog shift out as fast as possible: Consider 22.5µm square pixels A few µm resolution possible for good SNR Readout speed limited by analog settling Array of 132X48 pixels High-speed ADC analog Pixel Array: Column select ganged row read & storage Low power only significant draw at readout edge 2

4 Prototype Test Bench Compact PCI (cpci) based 3

5 Sampling Cycle Pixel array complete acquisition (fr1/fr2) 8448 samples transferred ~33ms cycle ~30 Hz acquisition Transfer to CPU on PCI bus (not DMA) ohm cable settling time dominated E E E E E E E E-02 Frame 1 Frame 2 8ms integration Pixel Readout Structure Analog reset MSa/s readout t (nsec.) 4

6 CAP CDS ( - ) Frame 1 - Frame 2 = 8ms integration - Leakage current Correction Can 30Hz 25% livetime ~fa leakage current (typ) ~18fA for hottest pixel shown Cosmic muon candidate! 5

7 Leakage Current # of pixels Before Irradiation 1-2fA/pixel common To be irradiated Leakage Current [fa] 6

8 Charge Collection Efficiency β- emitter Landau fit ~10µm Epi bulk 316keV e- de/dx ~ 323eV/µm mip de/dx ~ 267eV/µm Pixel Collected Deposited Energy Will Check After Irradiation 7

9 Charge Spread (pre-rad) Peak only 3X3 pixels 5X5 pixels 7X7 pixels 8

10 Recent progresses Pixel by pixel triggering. Generate mean and sigma of pixel array. New triggering scheme. Towards beam test run: Need to run several detectors in parallel. Upgrade firmware and data acquisition to handle multiple detectors. Irradiated detectors are back! 200 Krad vs 2 Mrad. 9

11 Beam Test Configuration 4x CAP1 beam definition 4x CAP2 tracking, efficiency 2 GeV π beam 10

12 Four channel setup 11

13 The four detector stack 12

14 Cosmic event Use now pixel by pixel triggering scheme. 15 Apr 04 Event in the 1 st layer 13

15 Irrad. detector: Leakage Current VERY PRELIMINARY After 200Krad Irradiation # of pixels 12-18fA/pixel common 13Apr04 Leakage Current [fa] 14

16 First correlated event! Use now pixel by pixel triggering scheme. Irrad detector 15 Apr 04 I ve cheated a bit: it s from Co60 15

17 C060 run 200krad detector!!! 15 Apr 04 16

18 Charge Spread (post-rad) Peak only 3X3 pixels 5X5 pixels 7X7 pixels 17

19 Plans for near future Irradiation studies Confirm leakage current level. 200 Krad vs 2Mrad. Run with irradiated detectors: radioactive sources / cosmics. Get ready for beam test: still much work to do. Stabilize 4 channel operation: reliable FB1 + cap1 assemblies. Software development: update multi-channel software. Online monitoring still to be done. New Front End Board F2 and Back End Board B2 ADC on F2, new data readout path, no more analog cable between Front end and acquisition card. Should improve noise levels and speed the data transfer. Gain experience with new F2 board (readout). Develop suitable firmware. Back next week 18

20 Back up slides 19

21 Charge Spread (pre-rad0) Peak only 3X3 pixels 5X5 pixels 7X7 pixels 20

22 Charge Spread (post-rad0) Peak only 3X3 pixels 5X5 pixels 7X7 pixels 21

23 Ctrl plots (pre-rad) Peak only 3X3 pixels 5X5 pixels 7X7 pixels 22

24 Ctrl plot (post-rad) Ctrl plot!!! 7X7 pixels 23

25 First Cosmic Event 1-MAR-04 Overnight Run Trigger = 60 ADC (not leakage I subt) 1 event in 13 hours 24

26 Source Check Cs137 10µC source: Counting rate jumped from 1 in 10 hrs to 50 in a few minutes β- emitter Definitely NOT a m.i.p! Continued beating on noise 25

27 Continuing Cosmics 4-MAR-04 Overnight Run Trigger = 45 ADC counts 7 events much better noise 26