Big BOSS Detector RD Natalie Roe LBNL DOE
Big. BOSS Detector R&D Natalie Roe, LBNL DOE Review of Big. BOSS Dec. 6 -7, 2011 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Topics • • • Big. BOSS Detector Overview Detector Requirements Pre-conceptual Design Choice Risks, trade-offs, optimizations R&D plan Summary 2 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Big. BOSS Detectors: Pre-conceptual Design Overview • Big. BOSS has 10 3 -arm spectrographs, covering wavelengths from 360 – 980 nm: — Blue 360 < l < ~600 — Vis ~600 < l < ~800 — NIR ~800 < l < 980 • Each arm has one large format (4 k x 4 k, 15 um pixel) CCD, for a total of 30, plus 10 -20% spares => ~36 CCDs — by comparison DES has 64, 2 k x 4 k, 15 mm pixel CCDs + spares • Each CCD has 4 readout amplifiers — total of 120 channels of low-noise analog readout, plus clock and control circuitry • Approx. 1 GB of data per exposure 3 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Topics • • • Big. BOSS Detector Overview Detector Requirements Pre-conceptual Design Choice Risks, trade-offs, optimizations R&D plan Summary 4 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Draft Detector Requirements Requirement Value Comment Format 4 k x 4 k 4 corner readout Pixel Size 15 mm fiber image well-sampled Diffusion < 6 mm rms FWHM ~ pixel size Quantum Efficiency > 80% 380 - 980 nm @ 150 K >10% 360 – 380 nm, 980 – 1050 nm Read Noise < 2. 5 e- @100 kpix/sec readout Dark Current < 5 e-/pix/hr @150 K Readout time < 40 s < 1 min telescope slew time Cosmetics < 10 bad cols bright or dark Charge Transfer Efficiency >0. 99999 parallel and serial Surface Flatness < 20 mm peak to valley; f/2 spectro optics 5 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Requirements Discussion • We assume standard 4 k x 4 k format with 15 mm pixels — available from several vendors + existing LBNL mask set — custom LBNL CCD designs are quite easy to implement • Quantum efficiency is main driver for detector selection • Read noise requirement also important especially for the Lyman-alpha forest analysis • Dark current specified to be <0. 5 read noise for 15 min exp • Other requirements and goals: — Readout electronics should be compact, low power, low noise — It is desirable to use same CCD and R/O for all 3 arms to minimize cost, complexity, and improve maintainability — Other important factors include cost & delivery 6 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Topics • • • Big. BOSS Detector Overview Detector Requirements Pre-conceptual Design Choice Risks, trade-offs, optimizations R&D plan Summary 7 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Pre-Conceptual Design Choice • Baseline choice for Big. BOSS detectors — e 2 v CCD 231 -84 4 k x 4 k with broadband coating for UV — LBNL fully-depleted 4 k x 4 k for Vis and NIR arms • develop buttable package based on 4 k x 2 k design • Detector readout based on CRIC ASIC developed for JDEM — 4 channel, analog shaping + CDS, auto-ranging 14 -bit pipeline ADC 8 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
QE and Absorption Length v l Big. BOSS Bandpass 106 90 105 80 104 70 103 60 e 2 v Broadband 50 Abs length 102 LBNL 250 um 10 40 1 30 10 -1 20 10 -2 10 10 -3 Photon Abs Length (mm) QE (%) 100 0 200 300 400 500 600 700 800 900 1000 Wavelength (nm) N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors 1100 1200 1300 9
Performance Measured in BOSS 4 k x 4 k LBNL CCD 4 k x 4 k e 2 v CCD Parameter Requirement Red 1 Red 2 Blue 1 Blue 2 Read Noise Blue: < 3 e. Red: < 5 e- 2. 1 e 2. 2 e 2. 5 e 2. 1 e- 2. 5 e 2. 4 e- 1. 8 e 1. 6 e 1. 7 e 1. 8 e- 1. 8 e 2. 2 e 1. 9 e 1. 8 e- Big. BOSS <2. 5 e~1 e-/pix/hr 1. 5 e-/pix/hr 2 bad cols 0 bad cols 4 bad cols Dark Current Big. BOSS Cosmetics Big. BOSS Blue: < 4 e-/pix/hr Red: < 8 e-/pix/hr <5 e-/pix/hr < 15 bad cols <10 bad cols 10 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
QE & Diffusion Characterization • QE and reflectivity — QE ~ (1 -R) • Pinhole projector for diffusion — virtual knife edge technique QE and diffusion testing Measured 4 mm rms for 200 um thick CCD @ 80 V; expect 5 mm for 250 mm thick CCD J. Fairfield et al, IEEE Trans. Nucl. Sci. , 53, 3877, 2006 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Readout Block Diagram • Compatible with p or n-type CCDs, 3 or 4 phase clocking, HV bias (CRIC) 12 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
CCD Frontend Electronics • Dual ASIC chip set provides complete readout, clock & control • CRIC: Four channels of dual slope correlated double sampler, three autoranges, 14 -bit ADC plus temperature monitoring, p- and n- compatible • CLIC: Fully programmable bias, clock and control waveforms • Both chips utilize LVDS interface for I/O, can operate in dewar CRIC CLIC Vog Generators Parallel Clock Drivers Voltage Reference SW RG Clock Drivers Digital Logic Serial Clock Drivers SW RG Serial Clock Drivers Vog Generators Temperature Monitor 6 bit DACs CRIC 3. 3 V Generators Vr Generator VDD Generator 14 Bit ADC Pre-Amp & CDS Multi-slope VSub Parallel Clock Drivers N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors Digital Logic
CCD Readout Prototypes • 2 PCB set for CCD R/O Front side Back side Clock driver board. HV bias generator. DACs. Monitoring readback ADCs. Bias voltages generation. CRIC 5 4 -channel CDS/ADC 5. 25” 3. 5” • CRIC/CLIC plug-in Developed for JDEM focal plane • uses CLIC ASIC for clock, control, bias generation • small enough to plug in behind CCD N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors 14
Topics • • • Big. BOSS Detector Overview Detector Requirements Pre-conceptual Design Choice Risks, trade-offs, optimizations R&D plan Summary 15 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Risks, Trade-offs, Optimization • Little risk in detectors/electronics for Big. BOSS — building on heritage from BOSS, JDEM R&D program • Trade studies: — evaluate alternate CCD vendors • eg Hamamatsu (licensed LBNL fully-depleted technology) — evaluate options for electronic readout • PCB vs CLIC ASIC for clock and control • Optimization studies — CCD temperature: QE in red vs dark current, hot pixels — CCD thickness: red QE v diffusion 16 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
CCD thickness optimization • Thicker silicon => better QE at long wavelengths • But also increased diffusion • Plan to study optimal choice for Big. BOSS red arm Chris Bebek 17 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Topics • • • Big. BOSS Detector Overview Detector Requirements Pre-conceptual Design Choice Risks, trade-offs, optimizations R&D plan Summary 18 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
R&D on Detectors & Readout • Continue R&D on readout prototype — characterization, cost analysis • Characterize e 2 v 4 k x 4 k — especially QE, diffusion — evaluate with prototype R/O system • R&D on LBNL CCDs — Implement buttable 4 k x 4 k package and characterize flatness — Red QE improvement => thicker silicon substrate — UV QE improvement => thinner backside coatings • one type of detector => reduction in cost and complexity, easier to trouble shoot, maintain • identical readout configuration, downstream software simplified — Read noise improvements • implement recent R&D advances into large format device 19 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Detector R&D: Contributors MSL: Co Tran, Guobin Wang, Nick Palaio, Steve Holland CCD Test Lab: Armin Karcher, Sufia Haque, Bill Kolbe, Julie Lee Cold Probing and Packaging: John Emes 20 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
QE and Absorption Length v l Big. BOSS Bandpass 106 90 105 80 104 70 103 60 LBNL AR 1 e 2 v Broadband 50 LBNL Thick 102 10 LBNL AR 2 40 Abs length 1 30 10 -1 20 10 -2 10 10 -3 Photon Abs Length (mm) QE (%) 100 0 200 300 400 500 600 700 800 900 1000 Wavelength (nm) N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors 1100 1200 1300 21
Optical Transmission - Theory • Detailed EM model developed by Don Groom to calculate — transmission — reflection — fringing (reflection from backside) • Results are in good agreement with measured QE on LBNL CCDs — models the ISDP contact layer plus Si. O 2/ITO AR coating • Used to predict how to improve QE, especially in the UV 22 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Optical Transmission v l 23 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
ISDP development 24 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
WAFER SUPPORTS BELIEVE TO RESTRICT GAS FLOW TO WAFER SURFACE BY BLOCKING SLITS IN WALL OF CAGED BOAT WAFER SUPPORTS MOVE TO AREAS AWAY FROM SLITS IN WALL OF CAGED BOAT TO ALLOW UNOBSTRUCTED FLOW OF PROCESS GAS N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
R&D on Read Noise 26 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
LBNL CCD Packaging Lab Flatness data on 4 k x 2 k CCD Class 1000 clean room and packaging fixtures N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors Cold probe station for device evaluation prior to dicing & packaging
Fixtures for Buttable CCD Packaging Chuck temperature controller Macro lens camera on glue dispensing side Epoxy dispensing syringe stage Macro lens camera away from glue dispensing side Substrate chuck Epoxydispensing unit CCD chuck 4 x Fiber optic lights Telecentric lens cameras for setting gaps, both sides 28 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
LBNL CCD Modules 4 k x 4 k BOSS, OSMOS spectrographs DES 2 k x 4 k CCD (FNAL package) 4 k x 2 k KOSMOS, COSMOS spectrographs JDEM/WFIRST 3. 5 k x 3. 5 k CCD and mixed technology (vis/NIR) prototype focal plane N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
4 k x 4 k packaging development • Based on design for JDEM CCD package • Similar package already developed for 2 k x 4 k format 4 k x 4 k front side and backside views 2 k x 4 k N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Topics • • • Big. BOSS Detector Overview Detector Requirements Pre-conceptual Design Choice Risks, trade-offs, optimizations R&D plan Summary 31 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
Summary • Detectors and readout electronics are well advanced and pose no significant risks • Pre-conceptual design baseline for Big. BOSS detectors employs fully-depleted 4 k x 4 k LBNL in Vis, NIR and e 2 v 4 k x 4 k CCD in UV arm • Readout electronics is based on ASICs developed for JDEM • Will carry out paper trade studies and detailed optimization of CCD thickness for red arm • R&D program will focus on — electronics prototype — detailed characterization of e 2 v detectors — 4 k x 4 k packaging development for LBNL CCD — thicker CCDs for enhanced red sensitivity — enhanced UV sensitivity of LBNL CCD 32 N. Roe 12/7/2011 Big. BOSS Instrument R&D Breakout - Detectors
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