SalSA Readout: GEISER & Digitizers. Gary S. Varner Univ. of Hawaii February 2005

Transcription

1 SalSA Readout: GEISER & Digitizers Gary S. Varner Univ. of Hawaii February 2005

2 Outline Transient Recording Have explored 3 techniques through prototype measurement stage For more than a year have been carrying on a dialog following the RICE2 effort Triggering Mention briefly with each Details strongly architecture dependent In all cases, a natural cluster/global split Alternatives?? (ponder and bring tomorrow) 1

3 Observing Askaryan Very snappy (antenna band limited) >GSa/s, GHz bandwidth Starting point: solutions developed for RICE & ANITA While RF pulses are strong, salt is much warmer than Antarctic ice Trigger << 3σ thermal noise Extended geometry ~320ps Measured, (-ve polarity) 2

4 GEISER (Giga-bit Ethernet Instrumentation for SalSA Electronics Readout) GEISER Philosophy Set low threshold Fill Gb/s ethernet link Event build at surface Pure digital transmission Trigger/Event building No custom, fast trigger Exploit telecomm Event building on PC farm 3

5 GEISER Board SERDES STRAW2 Interleaved delay lines Phy Ethernet 4kSa/event (4kB reduced) 200Hz trigger rate sustained 4

6 STRAW2 Chip Self-Triggered Recorder Analog Waveform (STRAW) 16 Channels of 256 deep SCA buckets DACs ADC Self-Triggering: -LL and HL (adj.) for each channel Optimized for RF input Microstrip 50Ω 8192 analog storage cells -Multiplicity trigger for LL hits On-chip ADC: 12-bit, >2MSPS Sampling Rate: 1-3GSa/s (adj.) Target input Bandwidth: >700MHz 32x256 SCA bank Trigger Sampling Rates >~8GSa/s possible w/ 0.25µm process Record length: ns External option: MUXed Analog out Die:~2.5mm 2 scalers 5

7 DALI Rev. B Evaluation Uncalib. Delay lines for interleaved sampling (>5.4GSa/s in lab) STRAW2 chips 6

8 GEISER Testing Poster presented at IEEE/NSS 2004 (Rome) 7

9 GEISER Trigger Simple multiplicity (N of M): Tr i g g e r R a t e s v e r s u s T r i g g e r T h r e s h o l d R a t e [ H z ] Trigge r Thr e s hold [s igm a nois e ] Cluster Case of 5 of 8 Can of course do corresponding plot for fixed Threshold, scan N 8

10 Salt Transient Digitizer (STD) Changes from GEISER Consider high-speed serial Cu output STRAW LABRADOR Features Variable attenuation Direct RF trigger (MAX9600) Initially single, eventually multi-buffer Make Compact Proof of principle 9

11 Salt Transient Digitizer (STD) LABRADOR 10

12 LABRADOR size = 2.5mm 2 8x Differential RF inputs 128x Wilkinson ADCs Analog Superbuffers 8 chan. * 256 samples 8x HS Analog out, 1x MUX out 11

13 LABRADOR Testing Sampling Freq. [GSa/s] LABRADOR Sampling Freq Freq. Adj. Voltage (ROVDD) [V] Easily covers range of interest Output ADC Code Avg. Labrador 2 T r a n s f e r C u r v e Average Noise (mv) I n p u t V o l t a g e ( V ) Noise Versus Bias GAINREF (V) y = x R 2 = Vneg = -.6V and R1 = 15 Ohm Vneg = -.6V and R1 = 0 Ohm Linear (Vneg = -.6V and R1 = 0 Ohm) LAB2 Amplitude [db] D i f f e r e n c e 3-15dBm sine wave Flat freq. response R F F r e q u e n c y [ M H z ] Linear Fit Residuals LAB Input Voltage (V) 9-10 bits dynamic range 12

14 STD Trigger Simple multiplicity: Send time stamp 1kHz cluster, 100us global trigger latency Tr i g g e r R a t e s v e r s u s Tr i g g e r T h r e s h o l d Cluster Trigger: send up only trigger packet Consider 4 deep buffer R a t e [ H z ] Trigger Threshold [sigma noise] Cluster 2-deep 3-deep 4-deep overflow 13

15 Both plausible -- however Strong preference to work at surface if can Attenuation/dispersion in coax unacceptable Analog over fiber optic an obvious choice: Very expensive Poor dynamic range Recent improvements: Price dropping Vastly improved linearizing circuitry Compact 14

16 Miteq Analog Optical Link M i t e q Analog Optical Link Amplitude [dbm] F r e q u e n c y [ M H z ] -74dBm M iteq Optical Link Potentially small, though we tested rack-mount version A m p l i t u d e [ V ] T i m e [ n s] Input Output 15

17 Miteq AO (II) M i t eq flatness across SalSA band A m p l i t u d e [ d B m ] dB -60dBm Fre q u e n c y [ M H z ] 2dB across band is spec max 16

18 Fiber-Span 1.5 T r acking Ge n e r a t o r S w e e p ( d B m out) -11 Receive Amplitude [dbm] Fiber-span F r e q u e n c y [ M H z ] Pulse R e s p o n s e [ Av t e c h ] 2.00E E E-01 A m p l i t u d e [ V ] 5.00E E E E-01 Input signal Fiber signal -1.50E E E T i m e [ n s] 17

19 Photonuum 2dB across band is spec max 18

20 Comparison Table V e n d o r Fre q r a n g e G a i n NF F l a tne ss 1dB com p r cost [db] [db] [db] [dbm] k$ M i t e q 50k - 3 GHz 10 to > 2 LBT-10M3G M14 F i b e r - s p a n MHz -5 (1m) 25? +/- 2.5 no spec ~ 1 AC300 (-131dBm/Hz, 100dB SFDR) P h o t o n u u m MHz / ~ 1 PH-1120 (not small) Single LNA possible with Miteq, other two require at least 2 stages of amplification 19

21 Fiber Utilization Multi-colors: Fiber-span: 7 channel CDMA RF Mixing: 20

22 Design Transcript Latest: Sept 2004 Design points along path to current architecture 21

23 Global architecture Many possible architectures 22

24 Summary Good starting point Will be an STD2 Consider the analog fiber option seriously Multiple choices for digitizer At surface, quite a bit of flexibility Plans Funding contingent, readout board Small system for test deployment Salt proto readout upgrade Trigger/Event building 23

25 Back-up slides 24