n e CC Sample Selection for the Near Detector CDR Tanaz Angelina - - PowerPoint PPT Presentation

ne CC Sample Selection for the Near Detector CDR

Tanaz Angelina Mohayai MPD Meeting

• Oct. 29, 2019

2019-10-29

• T. A. Mohayai

2

ne CC Sample Selection Plans

Motivation for a neCC sample selection for the CDR: In LArTPC, nmCC p0s can be misidentifjed as neCC Use HPgTPC to constrain LArTPC’s nmCC p0 backgrounds: p0s rarely convert in HPgTPC p0s that do convert, primarily convert via Dalitz decay so the

• utgoing e+e- pair can be sign tagged

To select a pure sample of neCC in HPgTPC, need to come up with a set of cuts – common backgrounds to neCC sample in HPgTPC: (already mentioned above) p0/g conversion Compton scattered electrons Delta rays from outside of fjducial volume (OOFV) interactions

gs from rocks

2019-10-29

• T. A. Mohayai

3

Fiducial cut: discard photon conversions too close to the HPgTPC boundary – this is to allow photon converted/Dalitz decay electrons to travel enough distance to be able to separate out in B-fjeld Angular cut: cut on the signature angular shape of the electron/positron pairs from g conversion – much wider opening angle compared to the primary electrons Energy cut: discard the mono-energetic gs that lead to Compton electrons (Leo has shown this in the past) Two-track from same vertex cut: discard electron-positron pairs that share the same initial track position Any suggestions?

Some Thoughts on the Cuts (Based on Past Experience)

2019-10-29

• T. A. Mohayai

4

ne CC Sample Selection Plans

Motivation for a neCC sample selection for the CDR: In LArTPC, nmCC p0s can be misidentifjed as neCC Use HPgTPC to constrain LArTPC’s nmCC p0 backgrounds: p0s rarely convert in HPgTPC p0s that do convert, primarily convert via Dalitz decay so the

• utgoing e+e- pair can be sign tagged

To select a pure sample of neCC in HPgTPC, need to come up with a set of cuts – common backgrounds to neCC sample in HPgTPC: (already mentioned above) p0/g

/g conversion

Compton scattered electrons Delta rays from outside of fjducial volume (OOFV) interactions

gs from rocks

2019-10-29

• T. A. Mohayai

5

Current Status of ne CC Selection

(for fjrst look at this) selected true neCC sample, then true primary electrons (“signal”), and true electrons/positrons from photon conversions (“background”) Shape differences between the “signal” electrons and the “background” electron/positrons can be used as cut – Dalitz decay electrons/positrons have wider and generally larger angles wrt incoming ns than primary electrons

2019-10-29

• T. A. Mohayai

6

Current Status of ne CC Selection

Cutting on high angles would not discard all of the background electrons/ positrons – so one can look at energy and position (e.g. cut on electrons and positrons that share the same vertex)

2019-10-29

• T. A. Mohayai

7

Current Status of ne CC Selection

Cutting on high angles would not discard all of the background electrons/ positrons – so one can look at energy and position (e.g. cut on electrons and positrons that share the same vertex)

momentum [GeV]

2019-10-29

• T. A. Mohayai

8

Summary & Next Steps

The plan is to come up with a set of cuts to reject the common backgrounds to neCC sample in HPgTPC – common backgrounds are: p0/g conversion Compton scattered electrons Delta rays from outside of fjducial volume (OOFV) interactions

gs from rocks

p0/g conversion and Compton scattered electrons have already been explored, what remains are the OOFV interactions that can be misidentifjed as neCC in HPgTPC Next steps: fjnish defjning a set of cuts and following that, quantify the selection effjciency

2019-10-29

• T. A. Mohayai

9

Addition Slides

2019-10-29

• T. A. Mohayai

10

Note about dE/dx-based PID

Need to be careful about cutting out low momentum/energy electrons from the sample (in an attempt to discard the background electrons to nueCC sample) – dE/dx-based PID loses effjciency towards higher momenta

10 35 1 3.5 0.09 0.35 0.03

From Tom Junk