kaons p ropagation t hrough n uclei

KaonsKaons P Propagation ropagation Through NucleiThrough Nuclei

NuruzzamanMississippi State

University

This work is sponsored by the Department of Energy

Office of ScienceGrant No.:DE-FG02-07ER41528

Jefferson Lab Hall C Users Meeting

31st January, 2009

Medium Energy Physics GroupAdvisor: Dr.Dipangkar Dutta

(http://ra.msstate.edu/~dd285/mep.html)

OutlineOutline

Nuclear Transparency

Nuclear Transparency with Pions & Kaons

Analysis

Preliminary Results

Nuclear TransparencyNuclear Transparency

Ratio of cross-sections for exclusive processes from nuclei to those from nucleons is termed as Nuclear Transparency

= Free (nucleon) cross-section

= Nuclear cross-section

Experimentally = 0.72 – 0.78, for p,k,

parameterized as = .˙.˙.. T= Aα-1

OutlineOutline



Analysis

Preliminary Results

Transparency Experiment withTransparency Experiment with

Experiment ran in July `04 and December `04 at Jefferson Lab

Data collected on LH2, LD2, 12C, 63Cu, and 197Au at Pπ of 2.8, 3.2, 3.4, 4.0 and 4.4 (GeV/c) Q2 of 1.1, 2.15, 3.0, 4.0 and 4.7 (GeV/c)2

JLab Experiment E01-107: A(e,e΄ )

The experiment was measuring pion transparency, however one gets kaons along with pions during data collection because kaons fall

within the coincidence window.

Spokespersons : D. Dutta & Rolf Ent

PionsPions KaonsKaons//

Hall CHall C

HMS- High Momentum SpectrometerSOS- Short Orbit Spectrometer

SOS

HMS

G0

OutlineOutline



Analysis

Preliminary Results

JLab Experiment E01-107 JLab Experiment E01-107 Typical coincidence time spectrum showing the

different particles detected

Kaon transparency from electro-production has never been measured before!!!

Coincidence time = Time taken by electron to reach SOS - Time taken by hadrons to reach HMS (within a 30ns window)

π

K+p

Coincidence Time (ns)

Particle Identification Particle Identification in the HMSin the HMS

Gas Cerenkov (Perflurobutane at 1 atm.)

(for pi/k separation)

Aerogel Cherenkov (Aerogel2 of n = 1.015)

(for k/p separation)

eA

Λ

e´

missing massA-

1

Particle Identification Particle Identification in the HMSin the HMS

e + p e’+K+ + Λ

e + A e’+K+ + Λ + X

Ee + Mp = Ee׳ + EK+ +EΛ

Pe + 0 = Pe’ + PK+ + PΛ

Energy & Momentum Conservation

Mass of Λ is MΛ = [EΛ2 - PΛ

2 ]1/2

Reactions

MΛ = 1.115 GeV/c2

MΣ = 1.119 GeV/c2

•Missing Mass: 1.10<Mx <1.15 for Λ,1.17<Mx <1.22 for Σ•Coincidence Time: abs(cointime+58.63)<0.26•Gas Cherenkov:SOS, N(p.e)>1; HMS, N(p.e)<1•Aerogel Cherenkov:HMS, N(p.e)<0•Other acceptances Hsyptar, hsxptar, hsdelta, ssdelta

Kaons after application of all constraints for H

target

Pions, Protons, Kaons (in

coincidence time vs missing mass ) using a loose Constraints

Pions

Kaons

Protons

MΛ= 1.115

MΣ= 1.119

Before & After Application of Constraints Before & After Application of Constraints on Kaon(Liquid Hydrogen) Dataon Kaon(Liquid Hydrogen) Data

Experimental Simulation Experimental Simulation “SIMC”“SIMC”

Ingredients of SIMC:

1. Realistic Models of the magnetic spectrometers including multiple scattering and energy loss in all intervening material encountered by the particles.

2. Decay of kaons in flight, and radiative corrections for all particles.

3. Model of the electro production of kaons from free protons

4. For heavier targets the free proton model is convoluted with a realistic spectral function for each target. Spectral function = probability of finding a proton inside the nucleus with a certain energy and momentum.

Transparency to be extracted asModelpExptp

ModelAExptA

σσ

σσ=T

/

/

Comparison of Liquid Hydrogen Data vs Comparison of Liquid Hydrogen Data vs Simulation(SIMC)applying all constraintsSimulation(SIMC)applying all constraints

Red – SIMCBlue – Data

All particle identification and acceptance constraints applied

σ = σ (Q2, W, t, ϕpq)

Q2 = Four MomentumTransferred Squared

Q2 Q2

Q2 Q2

SIMC Λ SIMC Σ

DataSIMC Λ + Σ

&Data

The ratio of Λ/Σ is determined from the LH2 data

Q2=1.1 GeV2 : 15.6 Q2=2.2 GeV2 : 9.7 Q2=3.0 GeV2 : 6.4




σ = σ (Q2, W, t, ϕpq)

W = Centre ofMass Energy w w

w w

SIMC Λ SIMC Σ

DataSIMC Λ + Σ

&Data




σ = σ (Q2, W, t, ϕpq)

t = Mandelstam Variable

t t

t t

SIMC Λ SIMC Σ

DataSIMC Λ + Σ

&Data




σ = σ (Q2, W, t, ϕpq)

ϕpq= Angle BetweenReaction Plane &Scattering Plane ϕpq

SIMC Λ SIMC Σ

DataSIMC Λ + Σ

&Data

ϕpq

ϕpq ϕpq

Pions, Protons & Kaons before application of all constraints for LD

target

Kaons separated after application of all

constraints on LD target

•Missing Mass: 1.09<Mx <1.22•Coincidence Time: abs(cointime+58.63)<0.26•Gas Cherenkov:SOS, N(p.e)>1; HMS, N(p.e)<1•Aerogel Cherenkov:HMS, N(p.e)<0•Other acceptances Hsyptar, hsxptar, hsdelta, ssdelta

Before & After Application of Constraints Before & After Application of Constraints on Kaon(Liquid Deuterium) Dataon Kaon(Liquid Deuterium) Data



Comparison of Liquid Deuterium Data vs Comparison of Liquid Deuterium Data vs Simulation(SIMC)applying all constraintsSimulation(SIMC)applying all constraints

Q2 = Four Momentum Transferred Squared

Q2

Q2 Q2

Q2

SIMC Λ SIMC Σ

DataSIMC Λ + Σ

&Data

σ = σ (Q2, W, t, ϕpq)

The ratios of Λ/Σ obtained from LH2 data are used to add the Λ-SIMC and Σ-SIMC yields




W = Centre of Mass Energy

SIMC Λ SIMC Σ

DataSIMC Λ + Σ

&Data

w w

w w

σ = σ (Q2, W, t, ϕpq)




t = Mandelstam Variable

SIMC Λ SIMC Σ

DataSIMC Λ + Σ

&Data

t t

t t

σ = σ (Q2, W, t, ϕpq)




SIMC Λ SIMC Σ

Data SIMC Λ + Σ&

Data

ϕpq= Angle BetweenReaction Plane &Scattering Plane

/

/

Expt ModelAA

Expt Modelpp

T

ϕpq

ϕpq ϕpq

ϕpq

σ = σ (Q2, W, t, ϕpq)



Comparison of Data vs Simulation(SIMC)applying Comparison of Data vs Simulation(SIMC)applying all constraints for Other Targetsall constraints for Other Targets

Q2 = Four Momentum Transferred Squared

Q2

Q2 Q2

SIMC Λ + Σ&

Data

σ = σ (Q2, W, t, ϕpq)Carbon Copper

Gold

OutlineOutline



Analysis

Preliminary Results

Systematic Uncertainties of E01107Systematic Uncertainties of E01107

3.9 3.8TOTAL

2.0 1.0Spectral Function

2.0 1.0Iteration

2.0 0.5Acceptance

1.0collimator

1.0 0.5Radiative Corrections

0.5Pauli Blocking

1.0 0.5Pion Decay

0.5 2.52.5Cut dependence

0.1 0.1Beam Energy

2.0 0.5Pion Absorption

0.5 0.5Tracking(HMS+SOS)

0.1Dead time correction

0.7Trigger(HMS+SOS)

0.1Coin blocking

0.5Target thickness

0.5 0.3Charge

0.4 - 0.7 2.0.0Particle ID

scale(%) total(%) point-to-point (%) Item

5.4

LD2 - Black

Carbon - Red

Copper - Green

Gold - Blue

Nuclear Transparency Nuclear Transparency vsvs Q Q22

Q2 ( GeV/c2 )

Preliminary Result

Cu, C, LD2 are shifted by -0.05,0.05,-0.10 in Q2 respectively

Analysis Plan Analysis Plan

•Determine the model dependent uncertainty

•Compare with theoretical calculations(Please contact your favorite theorist )

•Write paper & publish results

This work is sponsored by the Department of Energy

Office of ScienceGrant No.: DE-FG02-07ER41528

ThanThank Youk You



σ = σ (Q2, W, t, phipq)


Missing Massmissing mass

missing mass

missing mass

missing mass

SIMC Λ SIMC Σ

Data SIMC Λ + Σ&

Data

kaons p ropagation t hrough n uclei

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