Study of three‐nucleon forcewith a new experiment of

a proton‐deuteron break‐up reaction

Yuya Akazawa, M. Fujita, R. Honda1, M. Ikeda, H. Kanauchi, K. Kobayashi1, T.Koike,

K. Miki, K. Miwa, Y. Nakada1, S. Ozawa, Y. Sasaki, K. Sekiguchi, H. Tamura

Department of Physics, Tohoku University, Sendai , Japan1Department of Physics, Osaka University, Osaka, Japan

NSMAT2016

Contents

Introduction• 3NF study ← p‐d break-up reaction• Detector system “CATCH”

p‐d reaction experiment @ CYRIC• Experimental condition• Simulated result• Preparation status

Summary

3NF and Neutron star• Importance of Three-Nucleon Force (3NF) for NS

Model dependent

A. Akmal, et al., PRC58, 1804 (1998)

neutron matter

2NF : realistic nuclear potential ⇐ 3000~4000 NN scattering experimental data

⇒more experimental data needed for 3NF, YN, YY

ρ0

Study of 3NF by a p‐d break‐up reaction

『p-d break-up reaction』

J. Kuros´-Z˙ołnierczuk et al., PHYSICAL REVIEW C66, 024003 (2002)

S MeV

[mb

/(sr2・

MeV

)]

2NN

One of the probes to revealthe nature of three-nucleon force (3NF).

p1

p2n

Φ12

p beam

p1

p2

n

(E1,θ1)

(E2,θ2)

beam

p+d→p+p+n

d target

θ1

θ2 2NF+3NF

Ebeam = 65 MeV

From side

From back

S : correlation between E1 and E2

S (MeV)

Study of 3NF by a p‐d break-up reactionSome observables

・Energy correlation dependence・Reaction angular dependence (θ1,θ2)・Φ12 dependence

(θ1,θ2) dependence Φ12 dependence

Detector with a large angle acceptance for multi-particles is required

(θ1,θ2)=(15°,15°)Φ12=180°

(25°,15°) (30°,15°)

(25°,20°) (30°,20°)

※ θ±1°, Φ±5°

Φ12=40° Φ12=60°

Φ12=120°

Φ12=140°

S. Kistryn et al., Phys. Lett. B641, 23 (2006).

S (MeV)

S. Kistryn et al., Phys. Rev. C68, 054004 (2003).

2NF2NF+3NF

2NF

2NF+3NF

Experimental data at 130 MeV d beam

As the first step, we will take data with an 80 MeV p beam.

Current experimental data of p‐d reactions

⇒ new data points with our new detector system

80 MeVMeV/nucleon beam

80 MeV

関口さん

Courtesy of K. Sekiguchi [1] K. Bodek et al., Few Body Syst. 30, 65 (2001)[2] St. Kistryn, et al., Phys. Rev. C 68, 054004 (2003)[3] H. Mardanpour, et al., Nucl. Phys. A 790 (2007), p. 426c

etc.

RIKEN, RCNP, KVI, IUCF

next page

“CATCH”We will use this detector system for the p-d experiment.

Advantages・Large acceptance (∵surrounding the target)・Many sets of (θ1,θ2,Φ12)

in one experimental setup・Multiple particle detection・Particle ID (p/d/μ・π)

Cylindrical Fiber Tracker・surrounding a target ・8 layers of scintillation fibers・three dimensional tracking⇒measure the scattering angle (σ=1°)

and the energy deposit (σ=20%@1MeV)

BGO calorimeter・surrounding the CFT・24 BGO crystals (30×25×400mm3) are used ⇒measure the kinetic energy

(σ=1%@80MeV)

Cylindrical Active Tracker and Calorimeter system for Hyperon-proton scattering

Production finished soon

“CATCH”We will use this detector system for the p-d experiment.

Advantages・Large acceptance (∵surrounding the target)・Many sets of (θ1,θ2,Φ12)

in one experimental setup・Multiple particle detection・Particle ID (p/d/μ・π)

Cylindrical Active Tracker and Calorimeter system for Hyperon-proton scattering

Production finished soond

p

E(BGO) [MeV]

ΔE

(Fib

er)

[M

eV

]

Cosmic ray

Prototype results of pp, pC scattering

experiment

p-d experiment @ CYRIC• Experimental condition• Simulated result

• Preparation status

p‐d reaction experiment with CATCH

Measurement of dσ/dΩ of the p-d elastic scattering and break-up reaction⇒ new data for 3NF

Purpose

Experimental setup To be performed at CYRIC, Tohoku Univ. in January 2017

are

mea

sure

d .

Elastic scattering

p beam80 MeV

d’

p’

CFT

BGO calorimeter

D2 gas target300 mm(t)

Commissioning of the CATCH system

p beam80 MeV

p

p

n

Break-up reaction

Event identification for elastic scattering and break-up reaction

Simulation

θ [deg.]

E(C

FT+B

GO

) [M

eV]

Simulated result (pd elastic)

Ed’(θ)

Kinematically calculated Ep’(θ)

Simulation

pd散乱も80 MeVのデータは未測定⇒②-3

シミュレーション結果(pd break-up)

beam

Event generation: p-d elastic scattering kinematics. Detector: CATCH configuration

※Energy resolution is taken into account.

Event ID

p and d are clearly separated.

Simulated result (pd elastic)

Total E [MeV]

CFT

ΔE

[MeV

]

p

d

Particle ID

Simulation: p‐d elastic scattering

Identification of elastic scattering events using the kinematically calculated energy.

p’

d’

pd散乱も80 MeVのデータは未測定⇒②-3

シミュレーション結果(pd break-up)

beam

dσ/dΩ can be obtained as a function of S

for various combinations of (θ1,θ2,Φ12)

Simulated result

Missing Mass

reconstructed fromthe two protons

break-up reaction can be identified using Missing Mass of n

Ep1 vs Ep2Simulated result (pd break-up)

Missing Mass (Event ID)

S axis

Ep1 [MeV]

E p2

[MeV

]Uniquely determined correlation

p_{low E} can’t be tracked.

※threshold can be decreased

Selecting (θ1,θ2,Φ12)

θ1=55±2.5°θ2=60±2.5°Φ=180±10°

Event generation: p-d break-up reaction

for several combinations of (θ ,θ ,E ,E

p

p

n

pd→ppXMassX

S MeV

Simulation: p‐d break-up reaction

Energy acceptance：higher than 20 MeV for both Ep1 & Ep2

Status of CATCHBGO

Completed an assembly of CFT last week !!

BGO calorimeter is ready

Half part(14 crystals)

400mm400mm

4 straight +4 spiral layers

CFT

Angular resolution σθ≃1°(prototype)Efficiency ≃ 98% (3rd straight layer)

≃ 96%(3rd spiral layer)

Energy resolution σE≃ 1%for 80 MeV p

Satisfactory performance

Expected performance

Two systems will be combinedinto CATCH next month

p

p

n

400 mm

beam

p’

CATCH the new horizon

To be studied after commissioning of CATCH

Λp scattering

3NF

The same method as ∑p scattering except for

p-d, p-3He, etc…elastic scattering & break-up

Baryon-Baryon interactionΣp scattering

3NF (T=3/2)

Originally designed to be used for this experiment in J-PARC

p-d reaction experiments with CATCH is just a starting point

CATCH + spectrometers

Cylindrically

Active

Tracker and

Calorimeter system for

Hyperon-proton

scattering experiment

• 3NF study for neutron star- p-d elastic scattering and break-up reaction are one of the probes.- dσ/dΩ of p-d reaction at 80 MeV beam will be new data.

• New detector system CATCH- Suitable for this experiment because of its large acceptance- Consisting of a Cylindrical Fiber Tracker and BGO calorimeters- The first operation and application

• Simulation- p/d are clearly discriminated. - p-d elastic scattering & break-up reaction are identified from the

kinematics and missing mass

• Preparation- CATCH will be all constructed next month.

⇒ The experiment will be performed in Jan. 2017

Summary

• CATCH specification z acceptance = 400 [mm]

Energy acceptance 5 ~ 180 [MeV]※exchanging or adding crystals ⇒maximum can be increased

Energy resolution σE(BGO) = 1% for 80 MeVσE(CFT) = 20 % for 1MeV

Angular resolution σθ≃ 1°

Time resolution(CFT) σtime ≃ 1 [ns]

Particle ID : p/d/μ,e,π※depends on particle energy

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