Photodisintegration of the Triton:
A Probe of the Neutron-Neutron Interaction
Triangle Universities Nuclear Laboratory
(TUNL)
C.R. Howell
A.S. Crowell
L.C. Cumberbatch
B. Fallin
F. Friesen
W. Tornow
NC Central University
M.W. Ahmed
B.J. Crowe III
D.M. Markoff
Jagellonian University
H. Witala
June 3-4, 2013
HIGS2 WS
1
Measurement of 1S0 nn-Scattering Length
NN  ¼ s  ¾ t
=0
nn  ¼ s  ¾ t = ¼ s
s 
4
(1 a nn  k rnn 2 )  k
2
k  0
2
2
a
a

 s  4  a nn
2


1 
2 
a
 0 .5 
2
 2
  0 . 055
a
 18 
 nn   a nn
2
June 3-4, 2013
HIGS2 WS
2
The neutron-neutron 1S0 Scattering Length
1. Highly sensitive to the nn potential strength
 V nn
 0 . 005 
V nn
 a nn
 0 . 10
a nn
CD Bonn (l=1.0)
ann = -18.8 fm
reff = 2.82 fm
H. Witala and W. Glockle, PRC 83, 034004 (2011).
r0-w mixing
2. Limits CSB
 a CSB  a
N
nn
a
N
pp
I  1 H em I  0  m u  m d  4 MeV
 a CSB  1 . 2  0 . 4 fm
G. A. Miller, B. M. K. Nefkens, and I. Slaus, Phys. Rep. 194, 1 (1990)
June 3-4, 2013
HIGS2 WS
3
Determinations of the 1S0 ann
Using - + d  n + n + g
- + d  n + n + g
ann = -18.5 ± 0.4 ± 0.3 fm C.R. Howell et al., Phys. Lett. B 444, 252 (1998)
ann = -18.6 ± 0.4 ± 0.3 fm Q. Chen et al., Phys. Rev. C 77, 054002 (2008)
ann = -18.6 ± 0.4 ± 0.3 fm B. Gabioud et al., Phys. Lett. B 103, 9 (1981)
ann = -18.7 ± 0.6 ± 0.3 fm O. Schori et al., Phys. Rev. C 35, 2252 (1987)
Average: ann = -18.6 ± 0.3 ± 0.3 fm
a nn   18 . 9  0 . 3  0 . 3 fm
N
(corrected for MMI)
Investigation of reducing theoretical error
A. Gardestig and D.R. Phillips, Phys. Rev. C 73, 014002 (2006)
Constrains value of ann with EFT:
J. Kirscher and D.R. Phillips, arXiv;nucl-th, 1106.3171v1
 a CSB  a nn  a pp   18 . 9 fm  17 . 3 fm  1 . 6  0 . 5 fm
N
June 3-4, 2013
N
HIGS2 WS
4
Results from Kinematically Complete nd Breakup Measurements
|ann| = 2.5 ± 0.8 fm
3 SD difference
June 3-4, 2013
HIGS2 WS
5
nd breakup: nn QFS
from: H. Witała and W. Glöckle, Phys. Rev. C 83, 034004 (2011)
nn QFS cross section at En=26 MeV
Data: measured at Univ. Bonn
A. Siepe et al., Phys. Rev. C 65, 034010 (2002).
Calculations: CD-Bonn NN potential
June 3-4, 2013
nn QFS cross section at En=25 MeV
Data: measured at CIAE
X.C. Ruan et al., Phys. Rev. C 75, 057001 (2007).
Calculations: CD-Bonn NN potential
HIGS2 WS
6
nn interaction strength and dineutron binding
from: H. Witała and W. Glöckle, Phys. Rev. C 83, 034004 (2011)
June 3-4, 2013
HIGS2 WS
7
3H
3-body photodisintegration
3H + g  p + n + n
1.2
AV18
AV18+UrbanaIX
exp Faul et al.
1.0
nnp
tot
[mb]
0.8
0.6
0.4
0.2
0.0
5
10
15
20
25
30
35
40
45
50
E [MeV]
The total cross section for three-body photodisintegration of 3H. This figure is
taken from the thesis of R. Skibinski. The data are from Faul et al, Phys. Rev. C 24,
849 (1981). . The calculations are by R. Skibinski The MECs are treated using the
Siegert theorem.
June 3-4, 2013
HIGS2 WS
8
Photodisintegration of 3H
June 3-4, 2013
HIGS2 WS
9
Experiment setup for 3H photodisintegration
3H
gas targets
wire chambers
80 cm
g-ray beam
silicon detectors
June 3-4, 2013
HIGS2 WS
10
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