EPIC Cal Meeting 26-27.10.2006
First attempt to derive deadtime of
EPIC-pn from FIFO reset counters
Michael Martin
E. Kendziorra, T. Schanz, A. Santangelo
26.10.2006
IAAT DEPMOSFET
EPIC-pn
deadtime from
Data
FiFo
Aquisition
Resets
M.Martin
M.Martin
Institutfür
Institut
fürAstronomie
Astronomie
und
und
Astrophysik
Astrophysik
1
Introduction
DEPMOSFET
DataMeeting
Aquisition
Summary
EPIC Cal
26-27.10.2006
Overview
•
•
•
•
•
•
Introduction
Data readout chain
Test setup
Measurements
First results
Summary and outlook
EPIC-pn
IAAT DEPMOSFET
deadtime from
Data
FiFo
Aquisition
Resets
M.Martin
M.Martin
Institutfür
Institut
fürAstronomie
Astronomie
und
und
Astrophysik
Astrophysik
2
Introduction
DEPMOSFET
DataMeeting
Aquisition
Summary
EPIC Cal
26-27.10.2006
Introduction to FIFO resets
FIFO reset leads to loss of data
• In orbit:
–
•
On ground:
–
•
•
•
•
possible explanation: maximum ionizing particle leads to saturation of on-chip amplifier stage
Effect was seen by illumination with radioactive Am-source (5 MeV Alpha)
Complete column is above lower energy threshold
FIFO in readout chain is filled with events from row additionally to normal events
FIFO overflow can occur, causing reset
How many frames are lost due to the reset?
Working plan:
• Look for correlation between Ax_Pmode counter and number of lost frames
• Correction factor on time for each mode (FF, eFF, SW, LW, Timing)
• Estimate dead time
correct effective time on source
EPIC-pn
IAAT DEPMOSFET
deadtime from
Data
FiFo
Aquisition
Resets
M.Martin
M.Martin
Institutfür
Institut
fürAstronomie
Astronomie
und
und
Astrophysik
Astrophysik
3
Introduction
DEPMOSFET
DataMeeting
Aquisition
Summary
EPIC Cal
26-27.10.2006
Data readout chain
EPIC-pn event data input
event word 1
FIFO reset
counter
event word 2
Reset FIFO
FIFO full
FIFO
(1024 x 16 bit)
max. 511 events
&
time word
time word 2
FIFO reset to prevent
data corruption
Time word is needed to
trigger CPU processing
CPU
&
electronics
EPIC-pn
IAAT DEPMOSFET
deadtime from
Data
FiFo
Aquisition
Resets
time word 1
M.Martin
M.Martin
Institutfür
Institut
fürAstronomie
Astronomie
und
und
Astrophysik
Astrophysik
4
Introduction
DEPMOSFET
DataMeeting
Aquisition
Summary
EPIC Cal
26-27.10.2006
Test Setup I
@ IAAT
lab-model of EPIC-pn
flight level hard and
software revisions
BUT
operating just one CCD
force FIFO overflow
by illuminating pn-CCD
with LED pulse
EPIC-pn
IAAT DEPMOSFET
deadtime from
Data
FiFo
Aquisition
Resets
M.Martin
M.Martin
Institutfür
Institut
fürAstronomie
Astronomie
und
und
Astrophysik
Astrophysik
5
Introduction
DEPMOSFET
DataMeeting
Aquisition
Summary
EPIC Cal
26-27.10.2006
Test Setup II
Comparison between frame times (FT) in flight and at IAAT
(FT are given in ms)
Mode
EPIC-pn
FT
IAAT-pn
FT
ΔT/FT
FF
73.4
72.0
-1.4%
eFF
199.2
170.0
-15%
LW
47.7
43.0
-10%
SW
5.7
5.7
0%
TM
6.0
6.0
0%
BU
EPIC-pn
IAAT DEPMOSFET
deadtime from
Data
FiFo
Aquisition
Resets
Not yet
tested
M.Martin
M.Martin
Institutfür
Institut
fürAstronomie
Astronomie
und
und
Astrophysik
Astrophysik
6
Introduction
DEPMOSFET
DataMeeting
Aquisition
Summary
EPIC Cal
26-27.10.2006
Test Setup III
Recording of the FiFo status
EPIC-pn
IAAT DEPMOSFET
deadtime from
Data
FiFo
Aquisition
Resets
M.Martin
M.Martin
Institutfür
Institut
fürAstronomie
Astronomie
und
und
Astrophysik
Astrophysik
7
Introduction
DEPMOSFET
DataMeeting
Aquisition
Summary
EPIC Cal
26-27.10.2006
Measurements
LED pulsed with Agilent AWG
Square pulse with external trigger
Amplitude:
2-6V
Period:
1 sec
Pulse width:
0.5-1msec
# of pulses:
100
1. HK-files processed with IDL-progamme (@go)
2. Extract time words and search for irregularities
3. Check if found # of time gaps equals # of pulses
4. Get the time difference of gaps
5. Compute # of lost frames
6. Get conversion factor from Ax_Pmode counter
EPIC-pn
IAAT DEPMOSFET
deadtime from
Data
FiFo
Aquisition
Resets
M.Martin
M.Martin
Institutfür
Institut
fürAstronomie
Astronomie
und
und
Astrophysik
Astrophysik
8
Introduction
DEPMOSFET
DataMeeting
Aquisition
Summary
EPIC Cal
26-27.10.2006
First Results
Mode
# FIFO Resets
(Ax_Pmode)
Missing Frames Conversion Factor
FullFrame
613
613
1
eFullFrame
600
613
1.0217
Large Win
582
602
1.0344
Small Win
-
-
-
634
1241
1.9574
Timing
Dead time = # FIFO Resets * CF * frame time
EPIC-pn
IAAT DEPMOSFET
deadtime from
Data
FiFo
Aquisition
Resets
M.Martin
M.Martin
Institutfür
Institut
fürAstronomie
Astronomie
und
und
Astrophysik
Astrophysik
9
Introduction
DEPMOSFET
DataMeeting
Aquisition
Summary
EPIC Cal
26-27.10.2006
Summary and Outlook
• First attempt to estimate dead time looks promising
• Larger data sets are needed
• Investigate strange behavior of Small Window mode
• Test with EPIC-pn flight spare model at MPE PANTER facility needed
for verification
EPIC-pn
IAAT DEPMOSFET
deadtime from
Data
FiFo
Aquisition
Resets
M.Martin
M.Martin
Institutfür
Institut
fürAstronomie
Astronomie
und
und
Astrophysik
Astrophysik
10

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