E02-109/E04-001 (Jan05): Analysis Update
Simona Malace Jefferson Lab
E02-109/E04-001 2005 - Jan05 Physics motivation Experimental setup Status of the analysis: Background analysis (SOS data) calibrations PID efficiencies pion contamination cross section extraction and parametrization Towards physics cross sections extraction calibrations PID efficiencies (calorimeter) Finalizing the analysis: to do list
Overview
Overview: E02-109/E04-001 2005
Experiment Target W range Q2 range L/Ts Publication
E94-110 H RR 0.3 – 4.5 yes nucl-ex/0410027
E99-118 H, D, C, Al, Cu DIS+RR 0.1 – 1.7 yes published (H, D)
E00-002 H, D DIS+RR 0.03 – 1.5 some in progress
E02-109 D RR+QE 0.2 – 2.5 yes analyzing
E06-009 D RR+QE 0.7 - 4 yes in progress
E04-001 - I C, Al, Fe RR+QE 0.2 – 2.5 yes analyzing
E04-001 - II C, Al, Fe, Cu RR+QE 0.7 - 4 yes in progress
Low Q2 run H, D, Al, C Delta+QE 0.02 – 0.25 no analyzing
Jan05: E02-109 and E04-001 - I
Rosen07: E06-009 and E04-001 - II
Rosen07: will publish a short paper on RA-RD
Jan05 and Rosen07: the 2 data sets will be combined and a long paper on analysis and global L/Ts will follow
6 GeV
12 GeV: E12-14-002 L/Ts on nuclei in DIS, medium modifications of R and of separated structure functions
L/T separations on nuclei in the resonance region: nuclear medium modifications of R
Deuteron/Neutron moments, quark-hadron duality in the neutron SF
Quark-hadron duality in nuclei, the EMC effect
Neutrino cross section model development (Minerna): constraints on nuclear medium effects
Low Q2 run Targets: H, D, C, Al QE + Delta region
< 5 % uncertainty 1.6 % p.-to-p. uncertainty
Physics Overview: E02-109/E04-001 2005
Jan05 data will be used in conjunction with Rosen07 data for global L/Ts on nuclear targets
Experimental Overview: E02-109/E04-001 2005
Inclusive measurement in Hall C, A(e,e’), unpolarized beam, unpolarized target
Targets: D, C, Al, Fe, some H Beam Energies: 1.2, 2.3, 3.5, 4.6 GeV
SOS -> background measurements (e+) E’ = 0.47 – 1.68 GeV/c, q = 20-70 deg (last data ever taken by SOS)
HMS -> cross section measurements (e-) E’ = 0.4 – 4.5 GeV/c, q = 10.7-70 deg
HMS trigger rates: up to 800 kHz
2 cross section extractions analyses: SOS (background) and HMS data
Calibrations, final replay, efficiencies, cross section extraction and parametrization, systematics - done
E02-109/E04-001 2005: Analysis Status
Charge-symmetric background: p0 and g production in the target yields a background of e+e- pairs; to obtain the background from secondary e- to the DIS e- we measure e+
g produces e+e- pairs in the field of nucleons (Bethe-Heitler) as it passes through material
p0 decays in (mostly) 2g or ge+e-
Ideally e+ measured with same spectrometer as e-; due to time constraints Jan05 used SOS for e+ and HMS for e- detection we need e+ cross sections
Jan05: largest contribution 15% at 2.35 beam energy; for all other beam energies < 4%
E02-109/E04-001 2005: Background Analysis SOS drift chambers calibrations - done
residuals = the difference between where the particle hit the plane after the drift distance correction and the projection of the track on the plane
E02-109/E04-001 2005: Background Analysis
SOS drift calorimeter, Cherenkov calibrations - done
Number of photoelectrons in the SOS Cherenkov
E02-109/E04-001 2005: Background Analysis
SOS with negative polarity: 20 runs at Ebeam = 4.6 GeV and Ep = 1.68 GeV/c
These runs are useful for PID calibrations and PID efficiency calculation because they contain a large, clean sample of electrons
no Cerenkov cut Cerenkov > 2 Cerenkov > 5
SOS - SOS -
A SOS Cherenkov cut suppresses most pion signal
ssshtrk: (0.9,1.1) scal_e1/ssp > 0.3
SOS Calorimeter cuts suppress most pion signal
Normalized energy deposition in the calorimeter
Number of photoelectrons
E02-109/E04-001 2005: Background Analysis
SOS with negative polarity: 20 runs at Ebeam = 4.6 GeV and Ep = 1.68 GeV/c
𝜀𝑐𝑢𝑡 =𝐸𝑣. (𝑠ℎ𝑠𝑢𝑚 > 0.7 && 𝑠ℎ𝑙𝑜 > 0 && 𝑛𝑝𝑒 > 10)
𝐸𝑣. (𝑠ℎ𝑠𝑢𝑚 > 0.5 && 𝑠ℎ𝑙𝑜 > 0 && 𝑛𝑝𝑒 > 10)
𝜀𝑤.𝑡𝑟𝑎𝑐𝑘 =𝐸𝑣. (𝑠ℎ𝑡𝑟𝑎𝑐𝑘 > 0.7 && 𝑛𝑡𝑟𝑎𝑐𝑘𝑠 = 1 && 𝑛𝑝𝑒 > 10)
𝐸𝑣. (𝑠ℎ𝑠𝑢𝑚 > 0.7 && 𝑛𝑡𝑟𝑎𝑐𝑘𝑠 = 1 && 𝑛𝑝𝑒 > 10)
Calorimeter cut efficiency: shtrack > 0.7 Cherenkov cut efficiency: npe > 2
𝜀𝑐ℎ𝑒𝑟. =𝐸𝑣. (𝑠ℎ𝑡𝑟𝑎𝑐𝑘 0.9,1.1 && 𝑝𝑟𝑠ℎ > 0.3 && 𝑛𝑝𝑒 > 2)
𝐸𝑣. (𝑠ℎ𝑡𝑟𝑎𝑐𝑘 0.9,1.1 && 𝑝𝑟𝑠ℎ > 0.3)
selects a clean sample of e-
E02-109/E04-001 2005: Background Analysis
no Cerenkov cut Cerenkov > 2 Cerenkov > 5
SOS + no Cerenkov cut Cerenkov > 2 Cerenkov > 5
SOS -
SOS + Cerenkov > 2 + calorimeter > 0.7
Cerenkov <= 1
Cerenkov > 2 + calorimeter > 0.7
Cerenkov <= 1
SOS -
SOS with negative and positive polarity: relative e- to p- production much larger than the e+ to p+ production
Normalized energy deposition in the calorimeter Normalized energy deposition in the calorimeter
tight PID cuts clean sample of electrons
Pion contamination non-negligible
E02-109/E04-001 2005: Background Analysis SOS with positive polarity: we use a SHLO cut to reduce the p+ signal
ELHI requires SHLO ELREAL requires either ELLO or ELHI SHLO = low cut on the total energy deposited in the calorimeter
Jan05 SOS trigger: ELREAL
A SHLO cut reduces the low energy p+ signal
more manageable
E02-109/E04-001 2005: Background Analysis
SOS with negative polarity: 20 runs at Ebeam = 4.6 GeV and Ep = 1.68 GeV/c
Cherenkov cut efficiency: 99.6 %; if the detector performance is constant over time, the cut efficiency will not change
PID efficiencies
The calorimeter cut efficiency is momentum dependent: need to use positive polarity runs
Selecting a clean sample of positrons with one tight PID cut is impossible
Select the “cleanest” sample of positrons and extrapolate to zero p/e ratio
E02-109/E04-001 2005: Background Analysis
The calorimeter cut efficiency is momentum dependent: need to use positive polarity runs
PID efficiencies
𝜀𝑐𝑢𝑡 =𝐸𝑣. (𝑠ℎ𝑠𝑢𝑚 > 0.7 && 𝑠ℎ𝑙𝑜 > 0 && 𝑛𝑝𝑒 > 10)
𝐸𝑣. (𝑠ℎ𝑠𝑢𝑚 > 0.6 && 𝑠ℎ𝑙𝑜 > 0 && 𝑛𝑝𝑒 > 10) 𝜀𝑤.𝑡𝑟𝑎𝑐𝑘 =
𝐸𝑣. (𝑠ℎ𝑡𝑟𝑎𝑐𝑘 > 0.7 && 𝑛𝑡𝑟𝑎𝑐𝑘𝑠 = 1 && 𝑠ℎ𝑙𝑜 > 0 && 𝑛𝑝𝑒 > 10)
𝐸𝑣. (𝑠ℎ𝑠𝑢𝑚 > 0.7 && 𝑛𝑡𝑟𝑎𝑐𝑘𝑠 = 1 && 𝑠ℎ𝑙𝑜 > 0 && 𝑛𝑝𝑒 > 10)
The extrapolation to zero p/e ratio is recorded as the “real” calorimeter cut efficiency
E02-109/E04-001 2005: Background Analysis
The calorimeter cut efficiency is momentum dependent: need to use positive polarity runs
PID efficiencies
The extrapolation to zero p/e ratio is recorded as the “real” calorimeter cut efficiency
e- runs
The calorimeter cut efficiency is parametrized as a function of momentum
E02-109/E04-001 2005: Background Analysis
Pion contamination
What we do typically:
If we can still identify the p peak after a Cerenkov cut for e- or e+ selection, we can calculate a scale factor to rescale the pion distribution
2003 HMS -
What is the contamination from the p+ signal after applying PID cuts for e+ selection?
Cerenkov < 2
Cerenkov > 2
p peak after Cherenkov > 2
p contamination from scaled distribution with Cerenkov < 2
Jan05 SOS +
A SHLO cut makes the application of this method possible
E02-109/E04-001 2005: Background Analysis
Pion contamination
What is the contamination from the p+ signal after applying PID cuts for e+ selection?
Two distributions: Cerenkov < 2 and Cerenkov > 2 + SHLO > 0 dashed lines: fits
If p peak prominent and at same location in both distributions, rescaling done at location of p peak
If not, 3 rescaling factors used (scal_et/ssp = 0.65, 0.7, 0.75) and results are statistically averaged
E02-109/E04-001 2005: Background Analysis
Pion contamination
What is the contamination from the p+ signal after applying PID cuts for e+ selection?
A global parametrization of the p+ contamination with momentum is obtained regardless of the target or beam enery
p+ contamination for C; the band represents the fit with systematic uncertainty
E02-109/E04-001 2005: Background Analysis
Cross section extraction
no cuts
Cherenkov > 2
SHLO > 0
𝑠𝑠𝑥𝑝𝑡𝑎𝑟 < 0.06
𝑠𝑠𝑦𝑝𝑡𝑎𝑟 < 0.04
ssdelta: (-10,15)
ssshtrk > 0.7
The e+ yield is selected with acceptance and PID cuts and binned in q and momentum
Inefficiencies, prescale factors, acceptance corrections, p contamination are all applied
Cross section is statistically averaged over the q acceptance after removing the q dependence via model (bin-centering correction)
before bin-centering
after bin-centering
E02-109/E04-001 2005: Background Analysis
Cross section extraction
The cross section is extracted as a function of momentum and a global parametrization per target and beam energy is obtained
𝑒𝑃1(𝜃) ∗ (𝑒𝑃2 𝜃 ∗(𝐸𝑏 −𝐸𝑝) − 1)
Several iterations are performed (bin-centering correction); the model is used for background subtraction
E02-109/E04-001 2005: Background Analysis
Cross section extraction
Uncertainty on physics cross section related to the background subtraction: worst case at 2.35 GeV beam energy, up to 3%
Uncertainty on physics cross section related to the background subtraction: below 1% for 1.2, 3.5, 4.6 GeV beam energies
E02-109/E04-001 2005: Analysis Status 2 cross section extractions analyses: SOS (background) and HMS data
Final replay
all replay parameters re-checked and logged – done replay all runs – done the status of the calibrations will be checked and logged, re-calibration: drift chamber,
Cherenkov, calorimeter - done
PID efficiencies
Calorimeter - done Cherenkov, this includes checks of the Cerenkov cut dependence versus acceptance Other efficiencies
Tracking, this includes checks of the tracking efficiency dependence within acceptance
Dead times, electronic & computer
Trigger: problems with a discriminator for one of the scintillators, needs offline re-engineering
Other
Kinematic offsets, luminosity scans Generate MC files and radiative corrections - done Acceptance studies Cross sections extraction: 2 methods will be used, ROSEN07 & JAN05 (MC method) Model iteration Systematics
E02-109/E04-001 2005: Physics Analysis
Calibrations: Cherenkov and Calorimeter
Calibrations checked, done.
From energy deposited in the calorimeter (normalized to the momentum) around the track
1 photoelectron
looks just as good for other targets
E02-109/E04-001 2005: Physics Analysis
PID efficiencies: calorimeter
Calculation and parametrization of the HMS calorimeter cut efficiency
The rate dependence will also be checked
Summary
L/T separations on nuclei in the resonance region: nuclear medium modifications of R
Deuteron/Neutron moments, quark-hadron duality in the neutron SF
Quark-hadron duality in nuclei, the EMC effect
Neutrino cross section model development (Minerna): constraints on nuclear medium effects
Jan05, E02-109 and E04-001 – I, sets to study:
Status of the analysis: Background analysis (SOS data) calibrations PID efficiencies pion contamination cross section extraction and parametrization Towards physics cross sections extraction calibrations PID efficiencies (calorimeter)
The rest will follow….