Measurement of pd breakup cross sections at E/A = 13 MeV in the

off-plane star configuration

Yukie Maeda (University of Miyazaki)H. Shimoda, K. Sagara, S. Kuroita, T. Sueta, Y. Eguchi, K. Yashima (Kyushu Univ.)

A. Nonaka, N. Fujita (Univ. of Miyazaki)

D. Ishikawa, K. Hatanaka, H. Okamura, A. Tamii (RCNP, Osaka Univ.)

FB19 2009/8/31

2

Introduction

Study of the three-nucleon system at low energy region DCS of elastic scattering

3NF effect is small

NN + 3NF+ Coulomb reproduce the data well

Kievsky et al, PRC64 (2001) 24002.

Spin observables still have some Spin observables still have some problems (Ay puzzle etc)problems (Ay puzzle etc)

ButButCross sections are explained Cross sections are explained

sufficiently !!sufficiently !!

3

pd breakup reaction @ low energy

Study at 13MeV for some configurations （ solid ： pd, open ： nd ）

Quasi-free scattering (QFS) Final state interaction (FSI)

Introduction of the Coulomb into the calculation improved the predictions.

Some discrepancies are left to be explained.

Space-star (SST) Large discrepancy between the data

of pd and nd can not be explained by the Coulomb effects.

The theoretical prediction overestimates the pd data about 20%.

A. Deltuva et al, PRL95 (2005) 92301.

SST

QFS

FSI

CD Bonn + +CoulombCD Bonn +

△

4

Off-plane star configurations

Definition in this talk:

The is the angle between p-beam axis and the equilateral trianglr plane which include the momentum of p1’, p2’, n’ in the c.m. system.

• α=90° Space Star.

• α= 0, 180° Coplanar Star.

• α≠0,180° Off-plane Star.

5

Data from Köln J. Ley et al, PRC73 (2006) 64001.

CD BonnCD Bonn + CD Bonn + +Coulomb

1H(d,pp) breakup measurement at Ed=19MeV (9.5MeV/A) at Köln 3NF effects slightly improve the theory by 5 – 8%.

The predictions with 3NF and Coulomb effects still overestimate the data up to 30%.

Off-plane-star anomaly

6

Motivation

We performed the measurements of 1H(d,pp) breakup reactions at Ed = 26 MeV at RCNP Off-plane star anomaly is truly exist or not?

Systematical study of the discrepancy between the data and the theory Measurements for some other configurations (SST, FSI) of pd breakup reacti

ons have performed at Ep = 13 MeV at KUTL tandem accelerator, Kyushu University.

Off-plane star configuration measurements of 2H(p,pp) at Ep = 13 MeV at KUTL.

Range of = 0 – 180 deg will be covered by the data of RCNP & KUTL

7

Experimental procedure

1H(d,pp) breakup reactions at Ed = 26 MeV 26MeV deuteron beam from AVF

Proton target ; CH2 (polyethylene)

Two proton detection; 3pairs of SSDs

Luminosity monitor dp elastic scattering

Configurations = 120, 140, 160, 180 deg

Skip beam line

d-beam

CH2

F.C.

Monitor

Left detectors

p1

p2

Right detectors

8

Setup

Two protons detection by using a pair of 3000 mt SSD (Si-Li)

d-beam CH2

F.C.Left detectors

p1

p2 Right detectors

RL R L R L

180° 22.0° 0.0° 180.0° 0.333 0.321

160° 22.7° 11.2° 168.8° 0.319 0.291

140° 24.5° 20.4° 159.6° 0.272 0.287

120° 27.1° 26.6° 153.4° 0.241 0.243

(msr) (msr)

Monitor SSD: = 35.0=0R =0.0306(msr) Monitoring of the target thickness by measuring the pd elastic scattering

Calibration of the solid angles of each detectors Measurement of the C+p elastic scattering at = 35.0 by using each SSD and Monitor-SSD

simultaneously

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Rotary target

Simulation At 20 r.p.m., the temperature of t

he target foil increases only 15 degrees.

Beam

Beam spot

Atm

osph

ere

Insi

de S

catte

ring

cham

ber

Motor

Rotation feedthrough

Beam Line

Deutron 　 26MeV 200nA , 0.3mg/cm2

Rotary target system Through magnetic coupling, a s

haft in a vacuum chamber is rotated by a motor in the air.

The target foil : 5cm diameter.

Rotation speed : 20 r.p.m.

Rotary target can be lift up in vacuum, and other foil targets can be used in turn.

10

Uniformity of the target thickness

Thickness of a CH2 rotary target was constant for 20 hours.

膜厚の変化

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

2000 2002 2004 2006 2008 2010 2012 2014 2016

Run Number

(mg/

cm

2)

Stationary CH2 target

25℃→100℃(Beam Intensity : 100nA)

Rotate CH2 target

25℃→40℃(Beam Intensity : 200nA)

Change of CH2 thickness

0 2.5 10 20Time (hour)

High luminosity was obtained without the decrease of CH2 target thickness!

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Analysis

Most of the data is the accidental coincidence events Event selection by using the information of the time

difference between p1 and p2

C(d,d)

H(d,p)

C(d,d1)breakup

H(d,d)

H(d,d)

Single energy spectrum E1-E2 spectrum after TOF gate

S-curve of true events

d-beam

E1 E2

CH2

detect detect

T1 T2

12

Results

DCS

Theoretical predictions can reproduce the data well.

13

Systematic error

Derivation of the data

monmon

mon

ettmon

mon

mon

ett

d

d

YS

Y

dSdd

d

srmbQN

Y

d

d

SQN

Y

dSdd

d

21

12

21

3

arg

arg21

12

21

3

]/[36.49 Sagara et. al, PRC50,576 (1994)

1, 2 +/- 2.6%

mon +/- 1.5%

Y12 +/- 1.0%

Ymon +/- 0.5%

total +/- 4.1%

List of the error source

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Angular & energy dependence

Ratio of data/calc. at the star configuration

We can not see the large anomaly in the backward region at 13MeV/A, which is different from the Köln data at 9.5MeV/A .

More experimental studies are needed to see the energy dependence of the anomaly.

This work

15

Summary

To study the off-plane star anomaly, we performed the experiment of 1H(d,pp) and 2H(p,pp) breakup reactions at E/A = 13MeV at RCNP and KUTL. Si-Li type SSDs were used for detecting 2 protons in coincidence.

Rotary target system allowed us to obtain high luminosity.

The differential cross sections for = 120 ~ 180 deg (RCNP) and 0 ~ 75 deg (KUTL) were measured.

From the comparison between the data and the theoretical predictions; The data at 13MeV/A can be well reproduced by the calculations includi

ng the Coulomb effects, which is different from the data of Köln.

It is better to perform the experiment at Ed = 19MeV at RCNP to confirm the large anomaly reported from Köln.

16

END

17

SCRE configurations

Off-plane star configuration =0 (coplanar star), 17.7, 36, 56 de

g

Two proton detection in coincidence by a pair of SSDs.

Differential cross sections and Tensor analyzing powers Normalization: dp elastic scattering

Rawdata; E3, E4, t

E1

E2

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実験値導出

微分散乱断面積

偏極分解能

monmon

mon

ettmon

mon

mon

ett

d

d

N

N

dSdd

d

QN

N

d

d

SQN

N

dSdd

d

43

34

43

3

arg

arg43

34

43

3

pd elastic scattering