Event Mode Data Acquisition System
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Transcript of Event Mode Data Acquisition System
Event Mode Data Acquisition System
Richard Riedel, Oak Ridge National Laboratory
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Event Mode In a Nutshell
Every neutron detected is time stamped and saved without histogramming.
Other variables are also time stamped producing a movie like data set at run end.
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Why Event Mode?
This what detectors do (where and when a neutron is detected)
“Electronic time-focusing of pulsed-source neutron chopper data: binning to minimize effects of proton pulse and chopper opening time variations” JM Carpenter NIM vol 429 2001
Pulse Probe Techniques
Cross-Correlation Techniques.
(Corelli, which measures single crystal diffuse scattering using cross correlation to provide elastic discrimination)
Offers novel approaches to typical data acquisition problems
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Histogram
Neutron Events
TOF
X,Y
Counts
Time, E, Q, d
Pixel Spectrum
T.O.F., Space bins
Frame n+1
Frame n
Original Space nor Time resolution necessarily preserved…histogramming is a destroyer of information
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Also Need Hardware Gating
from preamp or shaper
gate control
Histogram neutrons only whentemperature is within some range of setpoint
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Event Based System Requirements
No hardware histogramming.
Ability to timestamp detected neutrons.
Log with time/date stamp ancillary variables (i.e. temp, magnetic fields etc.).
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Event Mode Paradigms
Gating is done at the reduction/analysis level not in the DAS hardware.
Histogramming is done at the reduction/analysis and can be modified as needed without affecting the underlying data.
scattering data
temperature logs
gated datasoftware with sort criteriadata from file stream
or live stream
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
d /sin
Pixel ID
tof
sine lookup
Event
Increment this binSoftware: a few multiplies, additions and if statements
Variables can be calculated without histogramming first.
Its easier to throw data out then to look at data that was never collected.
Could put a software gate here.
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Event Mode Data Format
Time Stamp [31:0] Uncorrected time of flight
Position Index [31:0] Pixel ID of detected neutron
Standard neutron event data generated by all detector electronics at the SNS
Pulse ID [63:0] Pulse ID from accelerator
Zero Based Starting Index [63:0] Index of starting neutron event structure that was produced with the above pulse ID
Standard pointer array which associates a pulse ID with a set of event data.
Array of event structure
+
Array of pulse info structure
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
SNS Implementation
Detector Electronics
Detectors
Common Data Format
Independent of Detector
System
UDPBroadcast
Common C++ Code
(Command Handling
Data transfer functions.)
Class xxx
Class yyy
Class zzz
C++ Abstraction Classes
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Broadcasting the Data Stream
Active Client (DFS)Passive ClientPassive ClientPreprocessor
Session Header
Header ACK
Data Packet #0
Packet #0 ACK
Guaranteed Delivery To One Point
Data Packet #n-1
Packet #n-1 ACK
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Transmission Benchmarks
Round Trip Time vs. Paylaod (SNS UDP protocol)
0
500
1000
1500
2000
2500
3000
0 10000 20000 30000 40000
Payload Bytes.
Sen
d T
ime
+ A
ck T
ime
(use
c)
with switch
witout switch
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Sample Live Views From Control Computer
SNAP .5M pixel Anger Camera
Mag. Refl. 2D He3 Gas Detector
Both instruments see same event format!
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Additional Listeners Can Do Real Time Independent Work
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Most Interesting Applications Require Additional Time Stamped Data
Preprocessor,Receives Events
from Electronics and adds
TOF correction.
Detector Electronics
Detectors
ControlComputer
P.P MasterMaintains listing of chopper
phasesPer pulse
DataFile Server
Data Streamed to both Control Computer and Data File Server (16.7 -100 msec time frame)
Both c.c. and dfsbin event data as directed
+ =
Position,TOF
Pulse Information Event DataChopper Phase
Temperature, Stress…
SNS DAS streams,event data……
Cross, AutoCorrelations,Dynamics, Phase Transitions,Kinetics and Transient Phenomenon
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Adding Chopper Phases/Other Variables
Requires DAS Hardware Sync signal.
Require Access To Accelerator Time Stamp Broadcast.
Requires Computer Clock to be synced with accelerator
High Frequency Signals
Low Frequency Signals
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Stress Strain Example
1000
33
1010
35
1020
31
1025
33
1000
34
1008
34
Strain Transducers
Stress Strain Preprocessor
Proton Pulses
Strain Sample Times
time
Stress Waveform
Sync. Pulse
PulseID Broadcast Data Set=two binary files
124567980
0
124568869
4
Data Set
PulseID
VULCAN will have the capability to do cross correlation technique
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
How Time Synchronization Is Done
Timing PC
Control Computer
Preprocessor
Satellite Computers:Chopper, Sample Environment etc.
Accelerator Time Stamp (60Hz)
Interrupt Based Driver/Service
(50usec latency)
NTP only
ETC
Tier 0Tier 1
Tier 2
NTP
NTP sets local time, UDP broadcast
sends accelerator time stamp
NTP to sync computer time,date clockUDP broadcast for computers that must associate additionaldata with accelerator time stamp (pulseid).
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Final File Set
+
Pairs of binary files
Neutron data
pulseid
Chopper Phases
pulseid
X Variablepulseid
not the same!
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
SQL Like Queries are Possible
SELECT pulses FROM run3100 WHERE temperature > 10 AND temperature < 20;
SELECT tof FROM run3100 WHERE pixelid=1101 OR pixelid=1102;
Would require a abstraction of file system. (Embryonic SQL queries available now for current values).
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Who Else Runs An Event DAQ?
Particle Physics.
Event Data
ATLAS DAQ system
Reduction,Data Sorting,
Analysis
NOMAD rates…up to 500MB/s