MARATHON ratio analysis

Tyler KutzStony Brook University

March 23, 2019

2nd Workshop on Quantitative Challenges in SRC and EMC ResearchBoston, MA

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1. Introduction

2. Target density correction

3. Radiative correction

4. Tritium β-decay correction

5. Ratios

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Introduction

MARATHON

• Measure σ(3H)/σ(3He) to extract Fn2 /Fp2

Extraction from deuterium and proton...

np p

n

pn

np

p• Sensitive to absolute magnitude of

nuclear effects

• Large model dependence at high x

MARATHON extraction...

np p

n

pn

np

p

• Sensitive to relative magnitude ofnuclear effects

• Reduced model dependence at high x

• Measure σ(3H)/σ(2H) and σ(3He)/σ(2H) to observe EMC effectin A = 3 nuclei

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Introduction

Status of ratio analysis

• Extracting three ratios:

• 3H/3He (Fn2 /Fp2 , d/u)

• 3H/2H, 3He/2H (EMC effect)

• Data covers range 0.2 < x < 0.8

• Status of ratio analysis:

• Ratios show good stability to changes in cuts, corrections

• Converging on first results for APS April meeting

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Target density correction

Density fluctuation

Credit: Nathaly Santiesteban, et al.(a) 3H Density Analysis. (b) 3He Density Analysis.

(c) 2H Density Analysis. (d) 1H Density Analysis.

Figure 10: Density analysis of 3H, 3He, 2H and 1H.

[16] J. Denard, A. Saha, G. Lavessiere, High Accuracy Beam Current MonitorSystem for CEBAF’s Experimental Hall A, Conf. Proc. C0106181 (2001)2326–2328, [,2326(2001)].

[17] K. B. Unser, The Parametric current transformer: A Beam current mon-itor developed for LEP, AIP Conf. Proc. 252 (1992) 266–275. doi:10.1063/1.42124.

Figure 11: Density Factor Ratios.

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(a) 3H Density Analysis. (b) 3He Density Analysis.

(c) 2H Density Analysis. (d) 1H Density Analysis.

Figure 10: Density analysis of 3H, 3He, 2H and 1H.

[16] J. Denard, A. Saha, G. Lavessiere, High Accuracy Beam Current MonitorSystem for CEBAF’s Experimental Hall A, Conf. Proc. C0106181 (2001)2326–2328, [,2326(2001)].

[17] K. B. Unser, The Parametric current transformer: A Beam current mon-itor developed for LEP, AIP Conf. Proc. 252 (1992) 266–275. doi:10.1063/1.42124.

Figure 11: Density Factor Ratios.

8

(a) 3H Density Analysis. (b) 3He Density Analysis.

(c) 2H Density Analysis. (d) 1H Density Analysis.

Figure 10: Density analysis of 3H, 3He, 2H and 1H.

[16] J. Denard, A. Saha, G. Lavessiere, High Accuracy Beam Current MonitorSystem for CEBAF’s Experimental Hall A, Conf. Proc. C0106181 (2001)2326–2328, [,2326(2001)].

[17] K. B. Unser, The Parametric current transformer: A Beam current mon-itor developed for LEP, AIP Conf. Proc. 252 (1992) 266–275. doi:10.1063/1.42124.

Figure 11: Density Factor Ratios.

8

(a) 3H Density Analysis. (b) 3He Density Analysis.

(c) 2H Density Analysis. (d) 1H Density Analysis.

Figure 10: Density analysis of 3H, 3He, 2H and 1H.

[16] J. Denard, A. Saha, G. Lavessiere, High Accuracy Beam Current MonitorSystem for CEBAF’s Experimental Hall A, Conf. Proc. C0106181 (2001)2326–2328, [,2326(2001)].

[17] K. B. Unser, The Parametric current transformer: A Beam current mon-itor developed for LEP, AIP Conf. Proc. 252 (1992) 266–275. doi:10.1063/1.42124.

Figure 11: Density Factor Ratios.

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• Beam-induced density fluctuationparameterized by quadratic function

• Details: arXiv:1811.12167(submitted to NIMA)

• Effect on ratios:

• Correction ≤5%• Uncertainty ≤0.5%

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Radiative correction

Model input

Credit: Hanjie Liu

Radiative correction requires input model:

• F d2 , F p2

1. Bodek2. NMC 1995 (Phys. Lett. B364 107-115,1995)

• 3H, 3He EMC ratio

1. Kulagin & Petti (no isoscalar corrections)2. SLAC EMC (isoscalar)

• SLAC EMC requires Fn2 /Fp2 to remove isoscalar correction

1. Fn2 /Fp2 = 1− 0.8x

2. CJ153. NMC 1992 (Nucl. Physics. B 371(1992) 3-31)1

Notation example:122 = Bodek + SLAC EMC + CJ15

1Neglects nuclear effects in 2H; not valid at high x6 / 11

Radiative correction

Model dependent uncertainty

0.2 0.3 0.4 0.5 0.6 0.7 0.8

x

0.998

1.000

1.002

1.004

RC

rati

o

H3/H2111/211

121/122

121/123

0.2 0.3 0.4 0.5 0.6 0.7 0.8

x

0.996

0.997

0.998

0.999

1.000

RC

rati

o

He3/H2

111/211

121/122

121/123

0.2 0.3 0.4 0.5 0.6 0.7 0.8

x

0.998

1.000

1.002

1.004

1.006

1.008

1.010

RC

rati

o

H3/He3111/211

121/122

121/123

• Model dependence of EMC ratios <0.5%

• Neglecting high-x NMC, model dependence of 3H/3He <0.5%

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Tritium β-decay correction

Target evolution

0 25 50 75 100 125 150 175 200

Days since Oct 23, 2017

0.00

0.01

0.02

0.03

f H

Boiling

MARATHON

SRC

• Tritium β-decays with half life τ1/2 = 4500± 8 days

• Parameterize helium contamination by helium fraction:

fH =nH(t)

ntot=n0H + n0

T (1− e−t/τ )

ntot

• fH ≈ 3% by end of spring run

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Tritium β-decay correction

Correction and uncertainty

Can obtain pure tritium yield in terms of raw yield Yraw and helium yield YH :

YT = Yraw

(1

1− 〈fH〉

)− YH

(〈fH〉

1− 〈fH〉

)where 〈fH〉 is charge-weighted helium fraction:

〈fH〉 =

∑QifH,i∑Qi

Effect on ratios:

• 〈fH〉 ≤ 2.5%

• Uncertainty ≤ 0.5%

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Ratios

D/p ratio

0.20 0.23 0.25 0.28 0.30 0.33 0.35xBj

1.55

1.60

1.65

1.70

σ(2

H)/σ

(1H

)

MARATHON D/p ratio

PRELIMIN

ARY

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Ratios

A = 3 ratios

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