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….