Gamma Tagging Module Updates(De-excitation gammas vs. brems)

Erin ConleyJune 14, 2017

De-excitation vs. Brems: Introduction• De-excitation gammas: Neutrinos interact with LAr,

produces ionized electrons and gammas• Bremsstrahlung gammas: Ionized electrons decelerate,

lose kinetic energy (converted to gammas)• Important features: directionality, isotropy

Gamma Tagger: Introduction• Working on algorithm to distinguish between bremsstrahlung and

de-excitation gammas• Reconstruction information• Study differences between nueCC events for the two types of gammas to

learn how to tag them• Simulated 10, 30, 50 MeV neutrinos in 1x2x6 geometry

• Generator: MARLEY• Reconstruction: standard_reco_dune10kt_1x2x6

Current Gamma Tagger + Plan• Current: gamma truth tagger in event display to view which hits

were caused by de-excitation or bremsstrahlung gammas• Module produces an association (art::Assns) between the reconstructed hits,

processes (strings)• Future: Might try to move toward associations already implemented in LArSoft, e.g., PFParticles

or Space Points

• Ultimately, move away from BackTracker, but use it for event display studies for now

• Event Display uses association to determine how the hits will be color coded

Example: 50 MeV

NoGammaTruthTagging GammaTruthTagging(JustBrems)

Brems

Event Display with Labels

• “B”forBremsstrahlung,“D”forDe-excitation

• Processnames“eBrem”and“primary”crowdthedisplay

• Previously,otherhitssettowhite(“off”)– thismakesitmoreobviouswherethehitsarelocated

Vector Sum Study: directionality, isotropy

• Looking at summed truth gamma energy deposition vectors

• Also: Summed dot products between gamma energy deposition vectors, electron track vector– Normalized all vectors when taking the dot products

• Study for differences between brems, de-excitations and over various energies

Vector Sum Study: Expectations for de-excitation gammas

Comptonscatter(energydeposition)

• De-excitationgammasemittedisotopicallyatinteractionvertex(left)• Formvectorsbetweenelectronvertexandenergydepositions(right)• Expectisotropic“cloud”ofthesedepositions,vectorsumshouldbesmall,~0

Vector Sum Study: Expectations for bremsstrahlung gammas

Comptonscatter(energydeposition)

• Brems emittedalongelectrontrack(left)• Formvectorsbetweenelectronvertexandenergydepositions,alsoalongtrack(right)• Expectforward-moving“jet”ofthesedepositions,vectorsumshouldbelargerandpositive

Event Display (Ortho3D): Energy Depositions, Brems• Truthinformation• Black:starting,ending

positionsofthetruthprimaryelectron;markedbyhand

• Blue:Bremsstrahlungenergydepositions(Comptonscattering,photoelectriceffect);markedbyhand

• Exampleofhowtheenergydepositionsforbrems look(brems areproducedalongthetrack;notshownhere)

Event Display (Ortho3D): Energy Depositions, De-ex• Truthinformation• Black:starting,ending

positionsofthetruthprimaryelectron;markedbyhand

• Blue:De-excitationenergydepositions(Comptonscattering,photoelectriceffect);markedbyhand

• Exampleofhowtheenergydepositionsforde-exgammaslook(de-exgammasproducedatelectronvertex)

Results: 30 MeV, vector sum study

BremsstrahlungDe-excitation

• 5000events• Oneentryper

event• Notalleventshave

gammaenergydepositions

Results: Multiple energies, vector sum study

10MeV30MeV50MeV

Results: Multiple energies, vector sum study10MeV30MeV50MeV

Vector Sum Study Conclusions• As expected, de-excitation energy depositions isotropic,

sum is centered on 0– Mostly independent of energy

• Bremsstrahlung energy depositions approximately along path of electron, give positive sum– As energy increases, vector sum increases

Results: 30 MeV, dot product studyBremsstrahlungDe-excitation

Results: Multiple energies, dot product study

10MeV30MeV50MeV

Results: Multiple energies, dot product study10MeV30MeV50MeV

Dot Product Study Conclusions• Bremsstrahlung dot product sums mostly positive,

centered at 1• De-excitation dot products sums both positive and

negative, flat (as expected)• Mostly independent of energy

Gamma Tagger: Next Steps• Use these conclusions/information to develop a tagging

algorithm • Move away from truth information, BackTracker; use

reconstruction information• Might look at more sophisticated isotropy quantification

– Handle curvature of track

Bonus: SNOwGLoBES smearing matrix• Use files made by Jason Stock to create SNOwGLoBES

smearing matrix for Argon 40• Charge distributions for entire range of energies (4.25-

99.75 MeV) were negative, multiple peaks– Tingjun Yang and Jason Stock helped to fix– Issues still arising with lower energies (4.25 MeV – 14.75 MeV);

running tests to diagnose problem• Hopefully will have the smearing matrix completed in the

near future!