W.Skulski Phobos Workshop April /2003 Digital Pulse Processor DDC-8 (Universal Trigger Module) for...

W.Skulski Phobos Workshop April/2003

Digital Pulse Processor DDC-8

(Universal Trigger Module)

for PHOBOS.

Wojtek Skulski

University of Rochester


Outline

•Trigger application in PHOBOS.•Description of the Universal Trigger Module DDC-8.•Two configurations:

1. Standalone module without DAQ readout.

2. VME front-end with DAQ readout.

•Response to scintillator pulses.

•Programming tools:

•FPGA programming tools.

•Embedded microprocessor tools.

•PC GUI programming environment.


Vertex and centrality definition in real time

• Analog signals: Paddles, Cerenkov, ZDC.• Logic signals from conventional NIM. • 1st level processing: DDC.• 2nd level processing: XLM, optional.• Accept/reject event within about 1 sec.

Online trigger

Vertex definition from TACs.T0 OR t, Paddle t,ZDC t.

PHOBOS @ RHIC

Centrality from paddle and ZDC.


Possible configurations

•Standalone Universal Trigger Module DDC-8.• 8 flash ADC channels + 41 logic I/O.

• Standalone data acquisition and histogramming.• Counting House interfaces: USB and JTAG.• Tunnel interface: RS-232.• Real-time decision: fast. • DAQ readout: no.

•The combo system UTM+XLM.• 8, 16, 24, or 32 flash ADC channels + many logic I/Os.• Real-time decision: slower due to “additional layer”. • DAQ readout: yes.• More complicated programming.


Signal OUT40 MHz * 10 bits

JTAG connector

microprocessor

FPGA

ADC 40 MHz * 10 bits (8 channels)

16 bidirectional TTL lines + 1 in(fast parallel interface to XLM)

Analogsignal IN8 channelswithdigital offsetand gain control

RS-232

Logic connectors NIM 16 lines IN, 8 lines OUT

USB

RAM500 kB

ECL clock IN(optional)


Single channel 12-bit prototype, development and testing

• Input channel for waveform capture, up to 65 Msamples/s.

• Output reconstruction channel for development and diagnostic.

• The channel design to be used for the 12-bit multichannel board.

Signal OUT

JTAG connector

USBprocessor connector

FPGA

Signal IN

ADC 65 MHz * 12 bits

Fast reconstruction DAC 65 MHz * 12 bits

Variablegain amp


Analogsection

Digitalsection

Correlationprocessor

User-defined17 I/O lines

OR

parallelinterface

Compositeinternaltrigger

Channel 1

Analogsection

Digitalsection

Channel 2

...Analogsection

Digitalsection

Channel 8

Optional external trigger (one of the 16 NIM in lines)

Internal triggersfrom channels 1…8

16*NIM in 8*NIM out

Analogsection

Digitalsection

Channel OUT

17*TTL in/out


8 chanXLM-72

900 MFLOPs4 MB

40,000 gates

DAQ8 chan

8 chan

32 flash ADCs

32*NIM out

8 chan

64*NIM in

On-board monitoring

1.2 million gatesin the FPGAs

On-the-fly datapreprocessing

Four independent parallel interfaces, 100+ MB/s.

VME

Flash ADC front end


# of analog input channels 8.# of analog output channels 1.# of logic inputs NIM 16. # of logic outputs NIM 8.# of in/out lines TTL 16+1.

Fast interfaces USB, parallel.Slow interfaces RS-232, SPI, I2C.Waveform memory 12 sec.On-board microprocessor 8 bits, 10 MIPS.Histogramming memory 0.5 MB.Packaging NIM, standalone.

Intermediate scale: SuperBall+DwarfBall.Medium scale: PHOBOS trigger.Small scale: table-top DPP systems, student research projects, DPP algorithm development.

DDC-8 features


Response to scintillation pulses

•DDC-8 firmware is under development.

•Results obtained with DDC-1, 48 MHz @ 12 bits.

•Very fast plastic BC-404: tpulse < tsampling.

•NaI(Tl): tpulse > tsampling.

•CsI(Tl): particle identification.

•Phoswich: two-component FAST-SLOW pulses.


ADC trace Sample value

Sample number20.0 30.0 40.0 50.0 60.0

1400.0

1600.0

1800.0

2.0E+3

2200.0

Samples

Signal from a Bicron BC-404 detectordigitized with the 1-channel prototype at 48 Msamples/s * 12 bits

Reliable digitization thanks to the antialiasing filter.

Excellent response to a very fast pulse

1 sample = 20.8 ns 1 sample = 0.2 ns

Tek screen for reference

Response to scintillator pulses: fast plastic scintillatorA typical pulse in PHOBOS environment


CsI(Tl) crystal

cosmic ray

phototube

teflon

Bicron BC-404FAST

SLOWADC trace Sample value

Sample number0.0 50.0 100.0 150.0 200.0

1700.0

1800.0

1900.0

2.0E+3

2100.0

SLOW

FAST

Samples

Signal from a phoswich detectordigitized with the DDC-1 48 Msamples/s at 12 bits

FAST clearly separated from SLOW

1 sample = 20.8 ns


Energy spectrumCounts

Filtered energy (arb. units)0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0 900.0 1.0E+3

0.0

50.0

100.0

150.0

200.0

250.0

Compton back-scatter

33 keV, Ba X-ray

77 keV, Pb X-ray

0.884 keV/bin

NaI 2" by 2"

662 keV, 137Cs

Energy 1

Signals from a Bicron 2”x2” NaI(Tl) detectordigitized with the 1-channel prototype at 48 Msamples/s * 12 bits

137Cs

Medium-fast scintillator pulses: NaI(Tl)

ADC waveformSample value

Sample number, 20.8 ns/sample400.0 420.0 440.0 460.0 480.0

1.0E+3

1500.0

2.0E+3

Samples NaI(Tl) 2" by 2"


-ray

1 cm3 CsI(Tl) + phototube 1-channel prototype at 48 Msamples/s * 12 bits

Note pulse shape dependence on type of radiation.

-particle

Response to scintillator pulses: CsI(Tl)


Sample number50.0 100.0 150.0 200.0

1900.0

1950.0

2.0E+3

2050.0

2100.0

gamma-ray

Samples


Sample number50.0 100.0 150.0 200.0

2.0E+3

2050.0

2100.0

alpha-particle

Samples


raditional slow-tail representation

1 cm3 CsI(Tl) + phototube

1-channel prototype

at 48 Msamples/s * 12 bits

natTh radioactive source

PID = TAIL / TOTAL

Note energy-independent PID

Particle ID from CsI(Tl)


Neutron Calorimeter SuperBall.16 m3 organic liquid scintillator.

• Online pulse shape analysis with DDC.

• Charged particle ID with CsI(Tl)/plastic.

• Neutron capture counting and timing.

• 1st level processing: DDC.

• 2nd level processing: XLM.

Research application: SuperBall + DwarfBall

4 charged particle detector DwarfBall/DwarfWall.Plastic+CsI(Tl) phoswich detectors.


Vertex and centrality definition in real time

• Analog signals: Paddles, Cerenkov, ZDC.• Logic signals from conventional NIM. • 1st level processing: DDC.• 2nd level processing: XLM, optional.• Accept/reject event within about 1 sec.

Online trigger

Vertex definition from TACs.T0 OR t, Paddle t,ZDC t.

PHOBOS @ RHIC

Centrality from paddle and ZDC.


Signal from a pocket NIM pulserdigitized with the DDC-8 at 40 Msamples/s * 10 bits

Excellent response to a very fast pulse seen with the “spy channel”

tpulse < tsampling.

Digitization made possible

by the Nyquist filter

ffilter = 1/4 fsampling

Latency = 300ns.

Input pulse

t0+300ns

How fast can we digitize the pulse?


Time budget

•ADC pipeline latency: 9*12.5ns = 112.5 ns.

•FPGA input: 25 ns.

•Nyquist filter: 100 ns.

•Tunnel -> CH propagation: 100 ns.

•Left-right time diff: 100 ns.

•TAC response: 300 ns.

•TOTAL = 0.74 s.

•Note: TAC output very likely can be made faster.


Software and firmware development tools

•Entry-level software development.• All development tools are free.

• FPGA: XILINX WebPack ISE.• Embedded micro: Keil C compiler, code restricted to 4kB.• PC GUI: Shareware edition of BlackBox Component Builder.

•Expert-level software development.• All tools discounted for universities.• FPGA.

•VHDL tools: XILINX ISE, full version.•Graphical tools: MatLab and XILINX System Generator.

• Embedded micro: Keil C compiler, full version.• PC GUI: Full edition of BlackBox Component Builder.


Obstacles and showstoppers

•Obstacles.• Firmware & software development takes time.

• Need an expert at the Phobos end.• Only one board exists, two more being assembled, all are already booked.• The 1st board has not been fully tested yet.

•Showstoppers?• Does Phobos need this tool?• Can Phobos designate an expert?• Recent deep cut in funding cannot be ignored.


Summary

•The technology is under control.•Glitches, if any, will be resolved.

•One DDC-8 assembled, works OK, but not yet fully tested.

•Two more boards being assembled.

•Firmware & software development will take time.

•A possible showstopper: recent cut in funding.

•Does Phobos need this device?•My personal belief: if there is need, the expert will step forward.

•The situation looks good, but not hopeless.

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W.Skulski Phobos Workshop April /2003 Digital Pulse Processor DDC-8 (Universal Trigger Module) for...

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