Transcript Real-time tools and algorithms for gamma spectroscopy

Real-time
tools and algorithms
for gamma spectroscopy
Ana Fernandes
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
OUTLINE
Gamma-Ray
The
My
Spectroscopy @ JET;
DAQ system for the upgrade program;
tasks;
Real
time algorithms;
Tests;
Results; Conclusions;
Future
Work.
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
GAMMA-RAY
SPECTROSCOPY
When fast ions:
• Fusion products
React with:
• ICRF-driven ions
 Plasma fuel ions
 Plasma impurities
• NBI-injected ions
intense γ-ray emission produced
γ-ray energy spectra
allows to:
identify nuclear reactions
distinguish fast-ion species in plasma
Infer their temperatures and densities
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
JET GAMMA-RAY
DIAGNOSTICS
Spatial distribution of the gamma-ray emission
Horizontal & vertical neutron/
gamma Camera
Two array of collimators (CsI(T1)
photo-diode, each LOS)
Tomographic reconstruction of the
Gamma-ray emissivity
Limitations: Count rate
=> obsolete electronics modules used
for analog processing and DAQ
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
JET GAMMA-RAY
DIAGNOSTICS
γ -Ray Energy Spectra
Horizontal view of the plasma
Vertical view of the plasma
BGO scintilator detector
NaI(TI) scintilator detector
•count rate;
Limitations
•detector response;
•energy resolution;
New gamma spectrometers for: high energy resolution; high efficiency; high
rate with large detection crystal
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
IPFN(IST) TEAM
TASK
DAQ system => will replace the current electronics used for the
JET Gamma ray diagnostics
Capable to perform high-resolution gamma spectroscopy at
very high count rate (few MHZ)
Capable to perform real time algorithms for data reduction and
digital pulse processing (PHA with PUR)
To fully exploit the flux increase provided by future high power
experiments at JET and ITER
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
THE DAQ SYSTEM
ATCA SHELF
CONTROLER
TRANSIENT RECORD MODULE
• 8 channels with :
•14-bit @ 400 MSamples/s (ADS5474)
or
•13-bit @ 250 MSamples/s (ADS5444)
• 4GB DDR2 SDRAM
• 2 FPGA (XC4VFX60-1152)
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
MY TASKS
Design and development of the FPGA code (FIRMWARE)
for the TR module to:
 Fulfill the demanded operational requirements;
 Perform REAL TIME ALGORITHMS FOR PULSE
PROCESSING @ FPGA
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
FPGA MAIN TASKS
Receive data from ADCS
 Configure clocks
Manage the trigger modes
Interface to local memory
Perform gigabit communication through PCIe links
Manage local memory data storage and reading
Process Data
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
FPGA BLOCKS DIAGRAM
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
CODE AND COMPILER
Compiler: ISE 10.1.03
(XILINX)
Code Language:
Verilog
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
FPGA OPERATING MODES
(1) Raw data mode
Data reduction/processing:
Real Time
Algorithms
(2) Pulse storage mode (pulse + TSTAMP)
(3) Processed data mode (pulse energy + TSTAMP)
To fill 2GB memory with 1 channel:
Novelty
should work
with
Parallelized
Data
•Raw Data mode @ 400MSPS => 2.5 seconds
•Processed mode @ 2Mevents/s => ~ 2 minutes!!
Great for long shots
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
ALGORITHMS FOR
PARALLEL DATA
High sampling rate
Data parallelized
Interleave channels
14-bit
@400MHz
PRE
BUFFER
PARALLEL
BUFFER
sampled at ¼ of the
sampling rate
4x16-bit
@100MHz
OPERATING BLOCKs
RAW DATA
PULSE DATA
PROCESSED
DATA
INTERFACE
DDR2
PCIe
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
PULSE STORAGE
ALGORITHM
1500
Parameters Example:
Amplitude
1000
500
•PTRG =16,
•PWIDTH =128
0
0
200
400
600
800
1000
1200
1400
Samples
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
PULSE PROCESSING
ALGORITHM
Based on the conventional timeinvariant digital trapezoidal shaper
(DTS)
Should be used in step signals
Ability to perform pulse processing
regarding parallel data as if it was in
series
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
PULSE PROCESSING
ALGORITHM (DTS)
DTS MODULE (1/2)
l
d k,
n (t) = v n (t) - v n -x (t - k) - v n (t - l) + v n (t - k - l)
delay-subtract units
k=0:15,k+1
Trapezoidal Shape
L=0:255,L+4
Rising (falling) Edge => K (~decay time constant τ)
Flat Top => |L-K|(~1/3 of τ)
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
PULSE PROCESSING
ALGORITHM (DTS)
DTS MODULE (2/2)
High Pass Deconvolver (HPD)
n
p n (t) = p3 (t - 1) +  dik,l (t)
1st Accumulator
i =0
l
rn (t) = p n (t) + M × d k,
n (t)
pole-zero cancelation ~ τ
Accumulator (HPD)
n
s n (t) = s3 (t - 1) +  ri (t)
i =0
2nd Accumulator
TRAPEZOIDAL SHAPE
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
PULSE PROCESSING
ALGORITHM (ER)
ED MODULE
0.5
When
Threshold
v 0 ( t  1)
v3 (t)
Volts
v2 (t)
ED( t )  0
v1 ( t )
0
v0 (t)
40
TRIGGER EVENT
50
Time (samples)
60
ED[0]
ED[1]
ED[2]
ED[3]
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
PULSE PROCESSING
ALGORITHM (ED)
ER MODULE
Inputs
ED(t)
If
If ED( t )  0
Sn(t)
Resolver starts
ER = E - B
E = flat top
B = baseline
ER (16-bit)
64-bit output
+
T_STAMP (48-bit)
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
PULSE PROCESSING
RESULTS
•Pulse event (raw mode)
0.4
Amplitude
0.38
@200MHZ
a) PULSE
0.36
0.34
0.32
0.3
0.28
5220
5230
5240
5250
5260
5270
5280
5290
Samples
•Trapezoid (calibration mode)
70
b) TRAPEZOID
68
66
64
Amplitude
Tests with AWG420
k=8, l=24
62
60
58
56
54
1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450
Samples
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
PULSE PROCESSING
RESULTS
Parallel Processing method @ FPGA results =>obtained for single energy
pulse plus noise
4
x 10
counts
fit 1
16
14
FPGA SPECTRA
Counts
12
10
FWHM =2,64
(400k events)
8
6
4
2
0
2
4
6
8
10
12
14
Energy Distribution
Compared with results from not parallelized algorithm @ standard PC
Conventional digital trapezoidal shaper validity is ensured!
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
PULSE PROCESSING
CONCLUSIONS
Processing operating method => increase in the number of useful
stored data
•To prevent data losses due to high sampling
rate
Parallelized
Processing Method
•To provide interleaved architectures
between channels
May be used as interface to
other algorithms
 Classical filter validity is ensured using the parallelized method!
Work presented in a Talk at the IAEA conference, 15-19 June 2009
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
PULSE PROCESSING
NEXT STEPS
•Improve/change the algorithm to perform:
•Baseline restoration
the performance of this filter drops if the
signal baseline is not stable
•Pulse pile up discriminator
•Less pulse shape dependency
Pile-up rejection with the current
algorithm
The JET GRS current photomultiplier
makes
the rise time of pulses slower
The algorithm performance drops
use the parallelized method with
other pulse processing algorithms
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009
REFERENCES
V.G.Kiptily et al., -ray diagnostics of energetic ions in JET, Nuclear Fusion 42, (2002), 999-1007;
M. Tardocchi et al, Gamma ray spectroscopy at high energy and high time resolution at JET, Rev. of
Scientific Instruments, 79 (2008) 10E524.
AdvancedTCA®, PICMG® 3.0 Revision 2.0, AdvancedTCA® Base Specification, March 18, 2005.
A. J. N. Batista, J. Sousa, and C. A. F. Varandas, ATCA digital controller hardware for vertical
stabilization of plasmas in tokamaks, Review of Scientific Instruments, 77, no. 10 (2006).
R.C. Pereira J.Sousa, A.M. Fernandes, F. Patrício, B. Carvalho, A.Neto, C.A.F. Varandas, G. Gorini,
M. Tardocchi, D.Gin, A. Shevelev, ATCA data acquisition system for gamma ray spectrometry,
Journal of Fusion Engineering and Design 83 (2008) 341–345.
V.T. Jordanov, Glenn F. Knoll, Digital synthesis of pulse shapes in real time for high resolution
radiation spectroscopy, Nuclear Instrum. Meth. Phys. Res. A 345 (1994) 337-345.
V.T. Jordanov et al, Digital techniques for real-time pulse shaping in radiation measurements,
Nuclear Instrum. Meth. Phys. Res. A 353 (1994) 261–264.
Doctorate in Fusion Science and Engineering | IPP Garching | Sept. 30 th, 2009