Upload
phamliem
View
215
Download
0
Embed Size (px)
Citation preview
Lesson Learned measuring the (π- ,Ar) & (K+,Ar) Total Hadronic Cross Section at LArIAT
Elena Gramellini - Yale UniversityJuly 11th 2018
LArIAT XS analyses in 4 simple steps:
1) Select the right particle in the beamline
2) Beamline-TPC Handshake
3) Apply the “thin slice method”
4) Correct for Backgrounds and Reco effects
12/07/18 Elena Gramellini -- Yale University 2
LArIAT XS analyses in 4 simple steps:
1) Select the right particle in the beamline
2) Beamline-TPC Handshake
3) Apply the “thin slice method”
4) Correct for Backgrounds and Reco effects
12/07/18 Elena Gramellini -- Yale University 3
LL: and account for the wrong ones
1) Select the right particle in beamline
12/07/18 4
LArIAT preliminaryRun II
Pos Polarity
Elena Gramellini -- Yale University
π/µ/e K p
LArIAT preliminaryRun II
Positive Polarity
Keep π: Mass < 350 MeV/c2
K: 350 MeV/c2 < Mass < 650 MeV/c2
1) Select the right particle in beamline
12/07/18 5
LArIAT preliminaryRun II
Pos Polarity
Elena Gramellini -- Yale University
π/µ/e K p
LArIAT preliminaryRun II
Positive Polarity
Keep π: Mass < 350 MeV/c2
K: 350 MeV/c2 < Mass < 650 MeV/c2
Indistinguishable π/µ/e
Beam Composition
12/07/18 Elena Gramellini -- Yale University 6
Beam Composition -60A
Shower Cut for ElectronsNo Cut for Muons.
Beam Composition -100A
LL: different beam conditions mean different compositions, leading to
different bkg
Beam Composition
12/07/18 Elena Gramellini -- Yale University 7
LL: if you can’t beat them, simulate them.
A reliable Beamline Simulation is important to to assess beamline backgrounds.
- Beam composition as a function of theincoming momentum at the TPC front face.
- Correct propagation of backgrounds in the “thinslice method” (more on this later)
LArIAT XS analyses in 4 simple steps:
1) Select the right particle in the beamline
2) Beamline-TPC Handshake
3) Apply the “thin slice method”
4) Correct for Backgrounds and Reco effects
12/07/18 Elena Gramellini -- Yale University 8
2) Beamline-TPC handshake
9Elena Gramellini -- Yale University12/07/18
Beamline objects- Momentum- Projection to TPC front face
TPC objects- Multiple Tracks with associated calorimetry.
LL: radial cut!
- Reject multiple matches- Keep track of incorrect matches… they are the only one that count!!!- Know where the momentum is measured in your beamline so to
account for energy loss between beamline and TPC.
2) Beamline-TPC handshake
10Elena Gramellini -- Yale University12/07/18
ELoss is the energy loss due to material upstream of the TPC (argon, steel, beamline detectors)
LL: - Minimize material in front of the TPC
- Accurate geometry survey
- Cross check of the geometry implemented in software
LArIAT XS analyses in 4 simple steps:
1) Select the right particle in the beamline
2) Beamline-TPC Handshake
3) Apply the “thin slice method”
4) Correct for Backgrounds and Reco effects
12/07/18 Elena Gramellini -- Yale University 11
If you get here, you have:- A pool of beamline candidates with a measured momentum
- A track selected in the TPC that represents your incoming pion. You know where the track ends and you know the energy deposited at each point of the track.
LArIAT XS analyses in 4 simple steps:
1) Select the right particle in the beamline
2) Beamline-TPC Handshake
3) Apply the “thin slice method”
4) Correct for Backgrounds and Reco effects
12/07/18 Elena Gramellini -- Yale University 12
If you get here, you have:- A pool of beamline candidates with a measured momentum
- A track selected in the TPC that represents your incoming pion. You know where the track ends and you know the energy deposited at each point of the track.
LL: do calorimetrycalibration ahead of time!
LArIAT XS analyses in 4 simple steps:
1) Select the right particle in the beamline
2) Beamline-TPC Handshake
3) Apply the “thin slice method”
4) Correct for Backgrounds and Reco effects
12/07/18 Elena Gramellini -- Yale University 13
The survival probability of a particle through a thin slab of argon is:
σTot = cross section per nucleon, δX = depth of the slab,n = the density
The interaction probabilityin a thin slab is the ratio of the number of interacting particlesto the number of incident particles.
3) Thin-slice method
14Elena Gramellini -- Yale University12/07/18
Since the slice is thin, we can Taylor expand and solve for the cross-section.
3) Thin-slice method
15Elena Gramellini -- Yale University12/07/18
The game here is understanding how many pions where incident on argon at a given energy and how many interacted at that energy.
16
N Incident , N Interacting calculationInteracting
IncidentKinetic Energy (MeV)
Kinetic Energy (MeV)
We follow the TPC track slice by slice
- The slice represents the distance between each 3D point in the track
- For each slice we ask: “Is this the end of the track?”
NO: Calculate the kinetic energy at this point and fill the “incident” histogram
Elena Gramellini -- Yale University12/07/18
Beamline SelectedK+ candidate
17
N Incident , N Interacting calculationInteracting
IncidentKinetic Energy (MeV)
Kinetic Energy (MeV)
We follow the TPC track slice by slice
- The slice represents the distance between each 3D point in the track
- For each slice we ask: “Is this the end of the track?”
YES! Calculate the KE at this point and fill both the “interacting” and “incident” histograms
Elena Gramellini -- Yale University12/07/18
Beamline SelectedK+ candidate
18
N Incident , N Interacting calculation
Elena Gramellini -- Yale University12/07/18
Beamline SelectedK+ candidate
LL: Stop thinking like a neutrino physicist J0) It’s very helpful to think of the slices in terms of single
independent experiments1) One beamline candidate corresponds to several independent
“thin target experiments”.2) Long tracks populate low energy bins3) Long tracks are easier to match! The matching affects the
population of NInt and NInc Incident
Kinetic Energy (MeV)
3) Thin-slice method
19
We take the ratio of the two histograms and calculate the raw cross section
=
Kinetic Energy (MeV)
Raw
Cro
ss-s
ectio
n (b
arns
)
Elena Gramellini -- Yale University12/07/18
Interacting
Incident
Kinetic Energy (MeV)
4) Correct for Background and Reco
20
=
Elena Gramellini -- Yale University12/07/18
Interacting
Incident
Kinetic Energy (MeV)
We evaluate the background and the reconstruction effects on the interacting and incident distributions separately
Kinetic Energy (MeV)
Cro
ss-s
ectio
n (b
arns
)
LArIAT XS analyses in 4 simple steps:
1) Select the right particle in the beamline
2) Beamline-TPC Handshake
3) Apply the “thin slice method”
4) Correct for Backgrounds and Reco effects
12/07/18 Elena Gramellini -- Yale University 21
Signal TopologiesσTot = σelastic + σinelastic+ σabs +
σcharge xc+ σπ-prod
22
Elastic Scattering Candidate
Absorption Candidate (π -> 3p)
Inelastic Scattering Candidate
Elena Gramellini -- Yale University 12/07/18
LArIAT Data
LArIAT Data
LArIAT Data
π Prod Candidate
LArIAT Data
Charge Exchange Candidate
LArIAT Data
Intrinsic Physics Background
23Elena Gramellini -- Yale University 12/07/18
π Decay Candidate
π Capture Candidate
π Beamline Decay (Secondaries)
LArIAT Data
LArIAT Data
LArIAT Data
+ residual electrons & muons
Beamline Background
“Intrinsic Physics” BackgroundDefinition of interaction: the tracking ends within FV.
π-Capture and π-Decay occur mainly at rest: select particles with
high incoming momentum.
12/07/18 Elena Gramellini -- Yale University 24
Surviving Event RatioLL: cut on the incoming particle momentum so that it cannot stop inside the TPC +Start the XS from KE > 100 MeV.
Alternative approach: change signal definition, correct for background (done in kaon analysis).
“Beamline” Background
LL: Muons and electron will appear differently in NInt and NInc
12/07/18 Elena Gramellini -- Yale University 25
“Beamline” Background
12/07/18 Elena Gramellini -- Yale University 26
0 200 400 600 800 1000 1200 Kinetic Energy [MeV]
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Inte
ract
ing
MC
pC
content -60ApEstimated
Muons x 2.0
Electrons x 2
Electrons x 0.5
Background Correction, Interacting
0 200 400 600 800 1000 1200 Kinetic Energy [MeV]
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Inci
dent
MC
pC
content -60ApEstimated
Muons x 2.0
Electrons x 2
Electrons x 0.5
Background Correction, Incident
+/-100% variation in electron
We know we underestimate the muons: +100% variation
XS Formula: Reconstruction Effects
12/07/18 Elena Gramellini -- Yale University 27
Correct Interaction ID
Missed Interaction
Early Stop
Reconstructed Track
Reconstructed Track
Reconstructed Track
Great, all the slices are at the right energy!
Inefficiency in NInt @ K.E.Int
Background in NInc for K.E. < K.E.Int
Background in NInt @ K.E.Int
Inefficiency in NInc for K.E. < K.E.Int
12/07/18 Elena Gramellini -- Yale University 28
0 200 400 600 800 1000 1200Kinetic Energy [MeV]
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Int
Î Eff Correction Interacting 60A Stat Unc
Eff Correction Interacting 60A Syst Unc
0 200 400 600 800 1000 1200Kinetic Energy [MeV]
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Inc
Î Eff Correction Interacting 60A Stat Unc
Eff Correction Interacting 60A Syst Unc
XS Formula: Reconstruction Effects
12/07/18 Elena Gramellini -- Yale University 29
0 200 400 600 800 1000 1200Kinetic Energy [MeV]
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Int
Î Eff Correction Interacting 60A Stat Unc
Eff Correction Interacting 60A Syst Unc
0 200 400 600 800 1000 1200Kinetic Energy [MeV]
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Inc
Î Eff Correction Interacting 60A Stat Unc
Eff Correction Interacting 60A Syst Unc
XS Formula: Reconstruction Effects
LL(1) Getting the correct MC truth takes more time than one would think… again, it’s the slice game!
12/07/18 Elena Gramellini -- Yale University 30
0 200 400 600 800 1000 1200Kinetic Energy [MeV]
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Int
Î Eff Correction Interacting 60A Stat Unc
Eff Correction Interacting 60A Syst Unc
0 200 400 600 800 1000 1200Kinetic Energy [MeV]
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Inc
Î Eff Correction Interacting 60A Stat Unc
Eff Correction Interacting 60A Syst Unc
XS Formula: Reconstruction Effects
LL(2) You shouldn’t correct for interactions you’re not sensitive to: what’s the minimum angle you can see?
What angles are invisible to us?
12/07/18 Elena Gramellini -- Yale University 32
0 200 400 600 800 1000 1200 Kinetic Energy [MeV]
0.7
0.75
0.8
0.85
0.9
0.95
1
1.05
1.1
All
s ° 5
s
Percentage of Cross Section with Interaction Angle > 5 Deg