Digital acquisition with DANCE - ORNL Physics Division · Digital acquisition with DANCE S. Mosby and A. Couture P-27; Nuclear Astrophysics and Structure Los Alamos National Laboratory
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Digital acquisition with DANCE
S. Mosby and A. CoutureP-27; Nuclear Astrophysics and StructureLos Alamos National Laboratory
July 29, 2015
FRIB Data Acquisition Workshop
LA-UR-15-25963
Operated by Los Alamos National Security, LLC for the U.S. Department of Energy’s NNSA
Slide 1 of 9
A Detector for Advanced Neutron Capture Experiments
160 BaF2 crystals w/ 4 crystalgeometries85% efficiency - calorimeterCapable of high trigger rates:250 kHz/ch or 1 MHz on arrayRadioactive / Rare targets(5 µg target in Jan. 2014)
Couple to NEUANCE for fissionneutrons (Stilbene) as well as�-spec (HPGe and LaBr3/CeBr3)Add fission fragment spectrometerfor complete fission experiments(CoFiE)?
Operated by Los Alamos National Security, LLC for the U.S. Department of Energy’s NNSA
Slide 2 of 9
Our new DAQ build
Upgrade from Acqiris DC265(cPCI, 4 ch, 8-bit, 500 MS/s, noon-board processing)Choice: CAEN VX1730B(VME64X, 16 ch, 14-bit,500 MS/s, on-board firmware)All channels independently trigger(no coinc requirements, but RUNgate on beam pulse)DANCE + NEUANCE + other = 14boards / 224 channelsMix PHA / PSD firmware ondigitizers depending on specificauxiliary detectorMIDAS-based acquisition software
Operated by Los Alamos National Security, LLC for the U.S. Department of Energy’s NNSA
Slide 3 of 9
Performance Gains
0.1
1
10
100
Len
gth
ofD
eadtim
eles
sR
ead
(ms)
1 10 100
Mean Time Between Crystal Hits (µs)
Current System
PSD, 100b/evt
PSD, 250b/evt
PSD, 500b/evt152Eu (6 µg/39 MBq)173Lu (50 µg)239Pu (50 mg)195Pt (35 mg)239Pu (1 mg)
DANCE Firmware Comparison
DANCE sees 20 beam pulses per second, PCI bandwidth limitedAcqiris-based DAQ to 512 µs time window when we really want 10 msFPGA firmware decreases data transfered over PCI busFull use of PCIe bus (black line) requires 1 optical link / 2 boards -desired performance needs ⇠300 MB/sec or 3 million peaks/sec to disk
Operated by Los Alamos National Security, LLC for the U.S. Department of Energy’s NNSA
Slide 4 of 9
BaF2 Pileup
750
800
850
900
Sig
nal
(arb
)
0 100 200 300 400 500 600 700
Sample Number (1 ns spacing)
Fast / slow components w/ 600 ps / 600 ns light curvesEnergy information is in slow decay, 150+ kHz rate creates ⇠20% pileupOld DAQ disentangled in software, now moving into firmware
Sense new pulseTruncate charge integralGenerate second firmware event
Operated by Los Alamos National Security, LLC for the U.S. Department of Energy’s NNSA
Slide 5 of 9
BaF2 Timing
4096
8192
12288
4096
8192
12288
4096
8192
12288
Sign
al (A
DU
)
4096
8192
12288
10 20 30Sample Number (2 ns/Sample)
4096
8192
12288
Fast component often saturatesfull scale of digitizer (full scaleoptimized for slow component)Modified CFD averages last 5points of waveform (solid green),projects back through fastcomponent to set CFD level(dashed green)⇠1 ns timing this way (⇠30%better than standard CFDalgorithm)Exploring use of analog filters tostretch leading edge, get morepoints to interpolate
Operated by Los Alamos National Security, LLC for the U.S. Department of Energy’s NNSA
Slide 6 of 9
Event Building
heapsort
Individual Channels Time Ordered Event Structures
Throughput concerns cause us to not perform any data sorting in thefrontendResult: each channel really is an asynchronous data streamPull whole file into memory (offline), heapsort (Numerical Recipes in C
1988) everything into a single data streamLoop through to build coincidences (shaded red)Detector IDs can be used for more complex operations based on detectortypeOther experiments using our software are developing online analysismodules
Operated by Los Alamos National Security, LLC for the U.S. Department of Energy’s NNSA
Slide 7 of 9
Looking forward
We see ourselves as DAQ users not developers, so we don’t want towrite our own VHDL
...but we like FPGA performance...For DANCE, DAQ throughput is key (end goal is ⇠3 million peaks/sec)
Firmware pileup handling will be extraordinarily usefulDon’t want the DAQ frontend doing any extra work
Cost: very asynchronous data files
Our timing algorithm is specialized and (for the moment) seems unlikelyto be implemented on an FPGA
Could a future digitizer have a “userland” DSP to process firmware eventsprior to readout?Benefit: don’t record any waveforms (better compression)
Operated by Los Alamos National Security, LLC for the U.S. Department of Energy’s NNSA
Slide 8 of 9
Acknowledgements
DANCE:
B. Baramsai (C-NR)T. A. Bredeweg (C-NR)M. Jandel (C-NR)J. M. O’Donnell (P-27)G. Rusev (C-NR)J. Ullmann (P-27)C. Walker (C-NR)
This work benefited from the use of the LANSCE accelerator facility. Workwas performed under the auspices of the U.S. Department of Energy at LosAlamos National Laboratory by the Los Alamos National Security, LLC underContract No. DE-AC52-06NA25396 and at Lawrence Livermore NationalLaboratory by the Lawrence Livermore National Security, LLC under ContractNo. DE-AC52-07NA27344.
Operated by Los Alamos National Security, LLC for the U.S. Department of Energy’s NNSA
Slide 9 of 9
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