measurement of pd breakup cross sections at e/a = 13 mev in the off-plane star configuration yukie...
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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
9
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!
11
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
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
14
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.
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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