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A2 collaboration meeting Feb 2011, Peter-Bernd Otte
A2 Collaboration Meeting Feb 2011 – Peter-Bernd Otte
Status New Trigger & Beam Polarimetry
e1
→e2
→
polarisedfoil
e1′→
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Brevity is the soul of wit
FPGA
~3 cm
~ meters
• = semiconductor chip
• FPGA = • many electronics modules (like OR, MLU)• cables
• no CPU!
“VUPROM” from GSIwith “Virtex 4” from XILINX
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part A: New Experiment Trigger
Setup of New Trigger
CB
PID
1st stage VUPROM
1st stage VUPROM
1st stage VUPROM
1st stage VUPROM
level converter
& cable
masterVUPROMcables
Exp. trigger
70nsComputation time:460ns for Multiplicity (LT = 98.7%)20ns for Coplanarity (LT = 100%)
Cellular Cluster Counter
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part A: New Experiment Trigger
• cellular logic• Steps
1. gather hit pattern (330ns)
2. Shrink clusters (60ns)(using set of rules)until no more changes
3. Count number of cells (20ns)= number of clusters
4. If desired cluster count trigger!
Multiplicity cluster algorithm
crystal scheme of CB
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part A: New Experiment Trigger
Algorithm universality
+ 180° rotated together 6x
Not all rules are valid for all crystals at all times.
1 2
3
1
5
2
3
14
2
3
14
5
2
3
1
510
6
2
3
+120° & +240° rotated
cure wholes
Shrink
CB TAPS
together 6x
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part A: New Experiment Trigger
Future
New CB trigger• works
since several months in parallel to the existing one
• awaits integration into L1/L2
• Remaining:purity and efficiency?
More sophisticated triggers possible with:
CB, PID, TAPS, MWPC in combination for L1/L2
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part B: Beam polarimetry
e- beam polarimetry
Tagger
e-
radiator
e
Measure degree of e- beam polarisationusing Moeller polarimeter
Good news:No big energy shift anymore! • now correct calibration for “new Tagger”• only ~1ch due to optics
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part B: Beam polarimetry
e- beam polarimetry works, but: mark “C”26
/11/
2010
12:
00
27/1
1/20
10 1
2:00
28/1
1/20
10 1
2:00
29/1
1/20
10 1
2:00
30/1
1/20
10 1
2:00
01/1
2/20
10 1
2:00
02/1
2/20
10 1
2:00
03/1
2/20
10 1
2:00
04/1
2/20
10 1
2:00
05/1
2/20
10 1
2:00
06/1
2/20
10 1
2:00
40
50
60
70
80
90
100
long
. deg
ree
of p
olar
isati
on i
n %
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part B: Beam polarimetry
• 100 histograms/FPGA, here 2 samples
• Reason: detector. • Proof: measured with two different electronics
shaky measurements
time diff. /ch time diff. /ch
low humming Strong humming
=
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part B: Beam polarimetry
• I5 and P7 channels of tagger:
• Humming = leads to biggest uncertainty in Moeller
Humming in Tagger (no noise!)
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part B: Beam polarimetry
• Why not constant?
e- source flux normalisation
Tagger section A B C D E F G H I J K L M N O P
e
e
N
N
~3% in pol. degree
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part B: Beam polarimetry
• 8th Feb work on beam dump dump position changed (?) 0.4% tagger magnet field change
0 to 2 channels shift in Tagger change in Moeller electronics and analysis needed
• Polarisation bit beam polarisation – possible to be obtained– MAMI energy dependent
Beam polarimetry
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part B: Beam polarimetry
• 5 VUPROMs in Tagger rack =1. Moeller electronics2. planned as monitor for linear photons polarisation:
indep. Tagger scalers with pair spectrometer as gate Patrik's talk
3. selection of single tagger channels for tests
Electronics in Tagger area
old
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part C: Problems
Problem in existing exp. trigger
Start of TDC at „CB Energy Sum“Start of TDC at „CB Energy Sum“
Stop of TDC at „TCS Trig“ / Exp. Trigger
Stop of TDC at „TCS Trig“ / Exp. Trigger
1% unclear
300ns
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
A2 Collaboration Meeting Feb 2011 – Peter-Bernd Otte
Status elog
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
• http://elog.office.a2.kph (user: a2online)
• elog from PSI (Stefan Ritt), open source, widely used und known– Many people in our group can assist– No text losses and locks anymore– Data from existing elog has been
imported
• Data reliability– uses infrastructure from KPH
computing group– virtual computer with RAID 5 (+ remote
hot mirror) and snapshots paperless future
• Everybody or group can have his/their own logbook
elog
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part C: Problems
The all new keyboard
New keyboard for all German PhD students. Makes life easier…
K.T. zu Guttenberg,Minister of Defence
“Wrote” >20% of his PhD with
Thanks for listening!
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part A: New Experiment Trigger
• Trigger = 2 hits in plane with incoming g (only azimuthal) |f1 – f2| = 180 deg
• divide CB into 48 azimuthal bins • “hardwired” trigger with ANDs and ORs
• immediate trigger result Livetime = ~100%• rate: 580Hz
(while M1+ = 16k, M2+ = 3.6k)
Coplanarity trigger
direction of beam
24xsublogic
OR
AND
Simulation by Cristina Collicott (D. Hornidge)
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part A: New Experiment Trigger
• Measured: Azimuth angle difference between hit channels in CB
Coplanarity trigger
Number of clusters (M) determined by FPGA logic
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part A: New Experiment Trigger
Setup of New Trigger: Multiplicity Trigger
CB(NaI)
PID
1st stage VUPROM
1st stage VUPROM
1st stage VUPROM
1st stage VUPROM
level converter
& cable
masterVUPROMcables
signal to all: Send full hit pattern
Exp. trigger
70ns 20ns 15ns
310ns 100-120ns+
Detailed hit pattern needed full readout!
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
• Rates:
• livetime: 98.7%
• Next step: determine purity and efficiency
• Same trigger algorithms can be extended to cover also TAPS
Multiplicity Trigger: Rates
New Trigger (CB only) Existing (CB and TAPS)
M1+ 20k 40k
M2+ 4.5k 6.0k
M3+ 1.6k 2.2k
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Teil 2: Trigger-Logiken
Bonn (2000) Mainz (2010)
Geschwindigkeit (nur Berechnung)
bis zu 10µs/Cluster 120ns insg.
Logik Zellularer Aufbau aber sequentielle Bearbeitung
Echt zellulare Logik
Im Vergleich
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part B: Moeller Polarimeter
• Use Moeller scattering– measure 2 coincident electrons
DAQ necessary
– Count asymmetry
beam polarity
Introduction electron beam polarimetry
BeamEEE 21
NN
NNA
e1
→e2
→
polarisedfoil
e1′→
e2′→
use Tagger
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Detectors of Tagger
Part B: Moeller Polarimeter
• Moeller radiator• Tagger• 4x VUPROMs
Moeller Polarimeter Setup
e1
→
e2
→e1 ′
→
e2 ′
→
1 352
VUPROM 1
VUPROM 2
VUPROM 3
VUPROM 4
AB
EF
GH
IJ OP
QR
ST
UV
Complete DAQ on a chip.Per FPGA:
24x TDC (resolution 50ps) & 50 histograms
A2 collaboration meeting Feb 2011, Peter-Bernd Otte
Part B: Moeller Polarimeter
• same e- energy and entry anglebutdifferent angles signs
Simulate Moeller electrons (Tagger optics)
0 50 100 150 200 250 300 350
-10
-5
0
5
10
15
pos. angle
neg. angle
Taggerchan.
ener
gy s
hift
in M
eV
(450 MeV beam energy)