Transcript ppt
Background for DC2
• Procedures for generating background
Toby Burnett
• Review: the PDR fluxes
• New guys on the block: Earth and CRflux
•…
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DC2 at GSFC June 05- T. Burnett
The procedure, practice for DC2
I run two jobs:
write_incoming creates a mcRootData file with only the
incoming particle. (No G4Generator, or recons). Two cases:
• 1 sec at given time after launch into 6 m2 as input to a sim/recon
job
• ~20 orbits into 0.0006 m2 to study orbit dependence
read_incoming analyzes an incoming root file.
• The random number seed is set for every event to a value
determined from the run and sequence numbers
• The full file is read
• Each event is fully simulated with G4Generator
• Events not satisfying the trigger or OnboardFilter are discarded
• The rest are reconstructed, results output to the tuple. Do not write out
the mc, digi, or recon files, assuming that they can be generated if
needed
In both cases, we use the DC2 orbit generated by Julie.
The above is included in the DataChallenge package
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DC2 at GSFC June 05- T. Burnett
The PDR sources
Used for PDR estimates of trigger rates and
background contamination.
Two versions, each with chime and various
combinations of power laws. For example:
•
<source name="backgndavgpdr">
<nestedSource sourceRef="chimeavg"/>
<nestedSource sourceRef="albedo_proton_avg" />
<nestedSource sourceRef="albedo_gamma" />
<nestedSource sourceRef="electronavg" />
<nestedSource sourceRef="albedo_electronpositronavg_total"/>
</source>
The backgndmaxpdr version is similar
Bottom line for trigger rate*:
• average ~ 3.5 kHz.,
• max~13kHz.
* lo-cal trigger is not properly computed
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DC2 at GSFC June 05- T. Burnett
PDR average spectra:
1 sec into 6 m2 all angles
All
protons
Source ID
0
1
2
3
4
counts
3931
7198
5545
35
6565
albedo
protons
primary
electrons
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DC2 at GSFC June 05- T. Burnett
albedo
gamma
albedo
electrons+
positrons
(but actually
only
positrons!)
Rates passing filter (for 1 s)
source
max
avg
chime
318
79
albedo_proton
107
36
84
77
6
2
75
41
590
235
albedo _gamma
electron
electron_positron
total
Note: not using deadtime yet.
For 25 s, expect 25% at 10 kHz!
Easy to turn on, will start it soon
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DC2 at GSFC June 05- T. Burnett
Earth: Dirk’s albedo gamma source
Earth
282->75
PDR used only the
limb: this has
contributions
from the disk.
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albedo_gamma_total
472->222
DC2 at GSFC June 05- T. Burnett
The DC2 orbit. Need to know where we are!
Incorporated in DataChallenge v2r*, GlastRelease v7r*
Simulating starting at t=2000:
FluxAlg.PointingHistory={"$(DATACHALLENGEROOT)/data/Gleam_survey.txt",
"2007-5-1 00:00:00"};
FluxSvc.StartDate="2007-5-1 00:00:00"; // launch
FluxSvc.StartTime=2000; // if both given, an offset
Why not just define average like for PDR?
Flexible, reproducible average
Models time dependence of rates, especially peaks
1 day / 16 orbits, plotting a point every 30 sec.
slewing rate ~7 deg/min
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DC2 at GSFC June 05- T. Burnett
Charged particles: the CRflux package
Written by T. Mizuno, based on balloon-flight experience,
AMS data, etc. Published.
Original code was a G4 “gun”. Converted to
Gaudi/FluxSvc
Models protons, electrons, positrons, He, gammas
Angular dependence
• secondary components isotropic
• Primary components isotropic except for Earth cutoff at
1350
• No azimuthal dependence, e.g. E/W effect.
Modifications/additions for GLAST/LAT
• notification of orbit position from the Gleam simulation:
update every 30 sec.
• Heavy ions (CNO) added by B. Lott.
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Extensive validation comparing output of current code
with AMS, BESS
DC2 at GSFC June 05- T. Burnett
CRflux Protons
Plots from T.
Mizuno
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DC2 at GSFC June 05- T. Burnett
CRflux electrons and positrons
Plots from T.
Mizuno
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DC2 at GSFC June 05- T. Burnett
Now add in the orbit, check generation
rates
The joboptions…
FluxAlg.area=0.0006; // cut down by factor of 10000 for testing
FluxSvc.DeltaTime=100000; //90*60=5400 is one orbit
// variable stuff follows here
FluxAlg.sources ={"CrTotalMix"};
FluxAlg.sources+={"Earth"};
FluxAlg.sources+={"clock"};
FluxAlg.AvoidSAA = true; //turn off during SAA
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DC2 at GSFC June 05- T. Burnett
The generated rates vs. time
p
e+
e-
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He
DC2 at GSFC June 05- T. Burnett
Does it make sense? Especially the positrons!
One orbit
Mizuno-san’s explanation:
“[the] positron flux is anti-correlated to protons. The reason is that, proton flux
(mostly primary) is lowest in geomagnetic equator (due to geomagnetic cutoff),
whereas e+ flux (mostly secondary) is highest (since they are more "trapped"
by geomagnetic field). Electron secondary flux has the similar geomagnetic
latitude dependence, but the flux is lower than e- (could be due to east-west
effect of primary protons) and the contribution of primary is relatively high.
This is why we don't see strong position dependence for e-."
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DC2 at GSFC June 05- T. Burnett
The spectra, orbit-averaged*
p
e-
e+
(Earth)
He
*thanks,
Julie!!
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DC2 at GSFC June 05- T. Burnett
Well, let’s see what happens to the LAT
rates
On to step 2. I sample selected seconds, every 1000, at the
full rates.
Note: this will be rerun, it was at
the wrong altitude, and orbit.
Will use the Condor batch
system on the UW/UCSC farm.
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2X the
PDR
rate!
DC2 at GSFC June 05- T. Burnett
What’s next?
Procedures
Study Rate “problem”
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Enable deadtime (how much? 25s?)
Verify that setting random number seeds is robust
Set up sampling job procedure
Fix CAL trigger bits
Enable ACD throttle trigger bits
Is the positron rate really what AMS measured?
Does it agree with the EGRET A-dome rate?
Test throttled rates
DC2 at GSFC June 05- T. Burnett