Measurements of Ay for the pd breakup reaction at 250MeV

Yukie Maeda (CNS, Univ. of Tokyo)T. Uesaka, T. Kawabata, K. Suda, S. Sakaguchi, Y. Sasamoto

(CNS, Univ. of Tokyo)

H. Sakai, K. Yako, M. Sasano, S. Noji (Dep. of Physics, Univ. of Tokyo)

K. Hatanaka, Y. Sakemi, A. Tamii, Y. Shimizu, Y. Tameshige, T. Matsubara,

M. Takechi (RCNP)

T. Sagara, T. Wakasa, M. Dozono, E. Ihara (Dep. of Physics, Kyushu Univ.)

K. Sekiguchi (RIKEN)

SPIN2006, October 2, 2006, Kyoto

2

Introduction; Three Nucleon Force (3NF)

Study of 3NF effects

Nuclear force (2NF,3NF)input

Faddeevequation

numericalresults

experimentalresults of 3NS

TM-3NFUrbana IX-3NF

CDBonn, AV18, Nijmegen I/II/93

Cross SectionSpin Observables

Binding Energyof 3H, 3He

N+d scattering at intermediate energy N+d scattering at intermediate energy region is good probe for 3NF effects.region is good probe for 3NF effects.

135MeV/A : DCS & A135MeV/A : DCS & Ayy data are well reproduced by introducing 3NF!! data are well reproduced by introducing 3NF!!

3

N+d elastic scattering at 250MeV

p+d (K. Hatanaka et.al, PRC66(2002)044002) & n+d (Y. Maeda PhD thesis) measurements at RCNP

● pd

　　　 : NN only 　　　 : NN with TM-3NF　　　 : AV18+UrbanaIX-3NF　　　 : CD-Bonn+TM’-3NF

Calculations by Prof. Kamada

4

Relativistic effects

Fully relativistic calculations by Witała et al.

Non-Rel.

Rel. NN potential

Lorentz boosted potential

Approx. １ Approx. ２

Relativistic effect is limited to the very

backward angles.

Large discrepancy indicates that we need other types of 3NF (?)

More studies of 3NF at 250 MeV are imporMore studies of 3NF at 250 MeV are important to understand this discrepancy.tant to understand this discrepancy.

5

pd breakup reaction

Why are Nd breakup reactions good at this energy?

E1

E2

tot

breakupela

Cross section becomes relatively large.

J. Kuroś et al., PRC66 (2002) 024003

Elastic scattering Integration of all p

Breakup reaction Select a point on the S-curve

It is important to select good kinematical configuration to search the detail of 3NF effect.

6

Analyzing powers

Around the final state interaction (FSI) configuration at 200MeVJ. Kuroś, Doctoral Dissertation (2002)

　　　 : NN only 　　　 : NN with TM-3NF　　　 : AV18+UrIX-3NF　　　 : CD-Bonn

+TM’-3NF

12 = 1 2

Measurements along the S-curve around the FSI configuration (1= 2 , 12 =0) is good probe to make a discrimination between the present 3NF models !!

Measurements along the S-curve around the FSI configuration (1= 2 , 12 =0) is good probe to make a discrimination between the present 3NF models !!

We chose the configuration of p1= n to avoid the Coulomb force acting between two nucleons in FSI.

7

Experiment at RCNP

p+d (p+n)+p @ 250MeV ; Differential cross sections & Ay

Two protons Detected by using double-arm spectrometer

Neutron in FSI Not detected

p

p

n

8

Experimental procedure

Configuration: (p1= n = 40 deg , 1n = 0 deg) (p1= 40 deg, p2 ～ 67 deg , 12 = 180 deg)

polarized proton beamEp = 250 MeVB.I. = 50 nA

polarization ~ 70 %

LAS = 40degEp1 = 50 ~ 115 MeV

GR ~ 67 degEp2 = 116 ~ 120 MeV

CD2 targetLiq D2 target

S-curve

S=0[MeV]

9

Liquid deuteron target

Target thickness 　 about 30 ｍｇ / ｃｍ 2 　Thickness of aramid foils 12m

Monitoring of the target thickness by the measurement of pd elastic scattering　 θp = θd = 50.8deg (LAB)

Calibration of the absolute values of the data

Deuterated polyethylene （ CD2) ５ 0 ｍｇ / ｃｍ 2 　Graphite

10

Missing Mass & S-curve

11

Results

Vector analyzing powers S = 7 MeV-bin

Statistical errors 　 Ay < 0.02

Differential cross sections

The analysis is in progress.

dp breakup at 250MeV

dp breakup at 200MeV

Preliminary

Preliminary

12

Summary

250 MeV pd breakup measurements were performed at RCNP. p1= n = 40 deg , 1n = 0 deg 　 configurations were measured by detect

ing two protons.

S = 30 – 125 MeV range including FSI.

Results Vector analyzing powers were obtained with Ay < 0.02.

Data will be compared with the theoretical predictions with/without 3NF.

The results of the differential cross sections are coming soon.

13

Thank you for your attention.

14

Results

15

Our proposal

To search the detail of the 3NF effects and make a discrimination between 3NF models, we propose to perform p+d (p+n)+p break up measurement at … Ep = 250 MeV

Observable: Ay

Configuration: (p1= n = 40 deg , 1n = 0 deg)

(p1= 40 deg, p2 ~ 67 deg , 12 = 180 deg)

Large 3NF effects

Difference between 3NF models

S-curve

S=0[MeV]

Experiments at RCNP• 250MeV d(p,p)pn ; Cross section & Ay• 100MeV/A p+d (pn)1So + p ; Cross section, Ay, Ayy, Axx, Axz

16

Kinematics

• 1, n = 29 – 31 deg (dashed lines)

• S = 80 – 170 MeV ; E1 = 115 – 50 MeV

• Data points Ay ; 7 points, Ay = 0.01 – 0.02 Ky

y’ ; 2 points, Kyy’

= 0.04

17

Coulomb interaction

It is difficult to include Coulomb force into the Faddeev calculations. Comparison between d+n Faddeev calculations and d+p data.

How large is the Coulomb effect in the intermediate energy region? Calculation including Coulomb force approximately. Data is well reproduced by including the Coulomb force at the forward a

ngular region. Large difference between calculations with/without Coulomb interaction.

NN:AV14 calculations by Prof. Koike

18

2-exchange 3NF models

parameter offcut:

factorformπNN)(22

2222

q

mqF NN

3NF model a b c d

FM

TM

Urbana IX

TM’

0.0

1.13

0.0

-0.87

-1.15

-2.62

-1.20

-2.62

0.0

1.05

0.0

0.0

-0.29

-0.60

-0.30

-0.60

p-wave

s-wave

b, d

a

c