Background for DC2

1. Background for DC2 • Procedures for generating background • Review: the PDR fluxes • New guys on the block: Earth and CRflux • … Toby Burnett DC2 at GSFC June 05- T. Burnett

2. 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 DC2 at GSFC June 05- T. Burnett

3. 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 DC2 at GSFC June 05- T. Burnett

4. PDR average spectra: 1 sec into 6 m2 all angles All protons Source ID counts 0 3931 1 7198 2 5545 3 35 4 6565 albedoprotons albedogamma primary electrons albedoelectrons+positrons (but actually only positrons!) DC2 at GSFC June 05- T. Burnett

5. Rates passing filter (for 1 s) Note: not using deadtime yet. For 25 s, expect 25% at 10 kHz! Easy to turn on, will start it soon DC2 at GSFC June 05- T. Burnett

6. Earth: Dirk’s albedo gamma source Earth282->75 PDR used only the limb: this has contributions from the disk. albedo_gamma_total 472->222 DC2 at GSFC June 05- T. Burnett

7. 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"; // launchFluxSvc.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 DC2 at GSFC June 05- T. Burnett

8. 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. • Extensive validation comparing output of current code with AMS, BESS DC2 at GSFC June 05- T. Burnett

9. CRflux Protons Plots from T. Mizuno DC2 at GSFC June 05- T. Burnett

10. CRflux electrons and positrons Plots from T. Mizuno DC2 at GSFC June 05- T. Burnett

11. 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 DC2 at GSFC June 05- T. Burnett

12. The generated rates vs. time p e+ e- He DC2 at GSFC June 05- T. Burnett

13. 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-."  DC2 at GSFC June 05- T. Burnett

14. The spectra, orbit-averaged* p e- e+  (Earth) He *thanks, Julie!! DC2 at GSFC June 05- T. Burnett

15. 2X the PDR rate! 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. DC2 at GSFC June 05- T. Burnett

16. What’s next? • Procedures • Enable deadtime (how much? 25s?) • Verify that setting random number seeds is robust • Set up sampling job procedure • Fix CAL trigger bits • Enable ACD throttle trigger bits • Study Rate “problem” • 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