Recent Experiments Involving
Few-Nucleon Systems
Werner Tornow
Duke University
&
Triangle Universities Nuclear Laboratory
Outline
• A=3 systems
g-3He 3-body breakup, n-n QFS in n-2H breakup, g-3H three-body breakup
• A=4 systems
N-3He Ay(q) elastic, n-3H s(q) elastic (using Inertial Confinement Fusion (ICF))
• A=5 systems
3H(d,g)5He/3H(d,n)4He
branching ratio (using ICF)
• A=6 systems
3H(t,2n)4He
neutron spectrum (using ICF)
• A=12 system
12C(g,3a)
and the 2+ excitation of the Hoyle 0+ state in 12C
• Outlook and Conclusion
Energy range considered:  50 MeV/N
1
A=3
g + 3He -> p + p + n
2
High-Intensity Gamma-ray Source (HIgS) @ TUNL
0.18-0.28 GeV
Electron Linac
0.18-1.2 GeV
Booster Injector
0.24-1.2 GeV
Storage Ring
g-ray beam parameters
FEL Undulators
World’s most intense accelerator-driven g-ray source
Intensity 103 g/s/eV on target
3
Values
Energy
1 – 100 MeV
Linear & circular polarization
> 97%
Spatial distribution after collimation (diameter)
10 – 25 mm
Pulse width (FWHM)
0.5 – 0.8 ns
Pulse repetition rate
5.58 MHz
Flux with 2% Eg/Eg ( 2 MeV < Eg < 5 MeV)
> 3 × 106
g/s
Flux with 5% Eg/Eg (5 MeV < Eg < 20 MeV)
> 7 × 107
g/s
7
Intensity
HIgS: Intracavity Compton-Back Scattering
2500
Eg =2032 keV
1500 Eg =26 keV
E/E = 1.3%
500
1950
2000
2050
Eg (keV)
Head-on collision: Eg ≈ 4γ2ħω
Example: Ee = 500 MeV  g = 978
lFEL = 400 nm
ħω = 3.11 eV
Eg = 11.9 MeV
Vladimir Litvinenko
4
Three-body photodisintegration of 3He with double polarizations at
12.8 and 14.7 MeV at HIGS/TUNL facility (Haiyan Gao’s group)
We detect
neutrons!
o Two Primary Goals:
o Test state-of-the-art three-body calculations made
by Deltuva [1] and Skibiński [2], and future EFT
calculations.
o
Important step towards investigating the GDH sum
rule for 3He below the pion production threshold :

I
GDH
d P
4 2a 2
A
= 
s N    s N   =
NI
2
MN
 thr 


Lorentz & gauge invariance, crossing symmetry, causality
and unitarity of the forward Compton scattering amplitude
[1] A. Deltuva et al., Phys. Rev. C 71, 054005 (2005); Phys. Rev.
C 72, 054004 (2005) and Nucl. Phys. A 790, 344c (2007).
[2] R. Skibiński et al., Phys. Rev. C 67, 054001 (2003); R.
Skibiński et al. Phys. Rev. C 72, 044002 (2005); R.Skibiński.
Private communications.
Gerasimov-Drell-Hearn
5
Goal II: GDH Sum Rule on 3He

d
2
2

a 2
s NP    s NA   =
N
2

MN

thr


th r


th r


496 b
GDH 3 He
217  39b
GDH 3 He

2  3GeV

A. Deltuva

?? HIγS @ TUNL
Extrapolated from low Q2 3He GDH (E94-010)
measurement @ JLab, (E97-110 much lower Q2)
 247  38b
GDH 3 He



2  3GeV
GDH 3 He

 31.9  9.6 b23GeV
GDH 3 He = Pn  

2 3GeV
GDH n  2  Pp  

2 3GeV
GDH p
= 0.87  35  2  (0.027)  (26)
M. Amarian, PRL 89, 242301(2002) J.L. Friar et al. PRC 42, 2310 (1990) N. Bianchi, et al. PLB 450, 439 (1999)
6
Apparatus of the Three-body
Photodisintegration Experiment
Beam
Direction
Optics Table
Beam enclosed
in vacuum
Laser light
D2O cell-flux
monitor not
shown in the
schematic
1. Automatically movable target and optical table
2. Detectors in mu-metal shielding tubes
7
High-pressure hybrid 3He target polarized longitudinally
using spin-exchange optical pumping
7 atm
40 cm long
Pyrex glass
tube
grays
8
9
Spin-Dependent Double Differential Cross
Sections at 12.8 MeV
Solid curve: R. Skibiński et al.
Dotted curve: A. Deltuva , A. Fonseça
10
Spin-Dependent Single Differential
Cross Sections at 12.8 MeV
(preliminary)
11
Spin-Dependent Total Cross Sections
and the GDH Integrand
This work 12.8
Deltuva et al.
872
777
0.146
956
872
0.131
1026
900
0.168
1079
970
0.146
This work 14.7
Deltuva et al.
Deltuva et al.
Skibiński et al.
Only 3-body part
10 year effort !
G. Laskaris et al., Phys. Rev. Lett. 110, 202501 (2013)
12
A=3
nn QFS in n + d breakup
&
g + 3H three-body breakup
13
En=26 MeV
n+d >n+n+p
n-p QFS
2H(d,n)3He
W. von Witsch, A. Siepe et al., 2002
For n-n QFS the
proton detector is
replaced by a
neutron detector
14
W. von Witsch, A. Siepe et al. (Bonn)
2H(n,np)n
np QFS
H. Witała
En=26 MeV
2H(n,nn)p
nn-QFS
H. Witała
15
En=25 MeV
X.C. Ruan (CIAE) & W. von Witsch (Bonn), 2007
China Institute of Atomic Energy
2H(n,nn)p
nn-QFS
H. Witała
3H(d,n)4He
16
En=19 MeV
TUNL np and nn QFS experimental setup
Proton
Detector
Neutron
Detector
Transmission
Foil Detector
2H(d,n)3He
Pulsed
Deuteron
Beam
Neutron
Beam
Deuterium
Gas Cell
C6D12
Target
CD2
Target
Proton
Recoil
Telescope
Neutron
Detector
Collimator & Shielding Wall
np QFS
setup
Neutron
Detector
nn QFS
setup
1.5 m
17
18
H. Witała & W. Glöckle
19
Parallel Session B1 (Monday afternoon)
Di-neutron searches
Yushi Maeda
Kazimierz Bodek
Sergey Zuyev
2H(n,p)nn
-absorption on 3He and 4He
d + T -> 3He + 2n
20
3H(g,p)nn
3H(g,n)2H
R. Skibiński
21
Photon induced three-body breakup of 3H > n +n +p
-108 keV
-323 keV
H. Witała
22
23
A=4
N – 3He Analyzing Power Ay(q)
at low energies
24
p – 3He
McDonald
1964
Fisher 2006
Alley 1993
Entem&Machleidt
Doleschall
A. Deltuva
25
n - 3He
En=1.60 MeV
dashed green
INOY04
dashed blue
AV18
En=2.26 MeV
En=4.05 MeV
solid orange
CD Bonn
En=5.54 MeV
dotted red
CD Bonn + 
A. Deltuva
En=3.14MeV
J. Esterline et al., PRL 110,152503 ( 2013)
26
Nucleon-3He elastic scattering
CD Bonn, 7.26 MeV INOY04, 7.73 MeV
p-3He
p-3He
n-3He
n-3He
27
Four-Nucleon Elastic Scattering
p - 3He
T=1
n - 3H
T=1
p - 3H
T=0,1
n - 3He
T=0,1
need data
need better data
28
A=4
n -3H elastic s(q) at 14.1 MeV
from
Inertial Confinement Fusion
(ICF)
OMEGA @ University of Rochester
29
30 kJ
1-ns square pulse
Yn = 5×1013
<Ti>n = 9 keV
qnt
SiO2 glass
shell burnt
away entirely
at bang time
n'
DT
3.5 m SiO2
20 atm
DT gas
t’
n
n
n'
425 m
qnd
d’
Elastically-scattered deuterons (d’):
n(14.1MeV) + D  n’ + d’ (<12.5 MeV)
Ed’ = (8/9) × En × Cos2qnd
Elastically-scattered tritons (t’):
n(14.1MeV) + D  n’ + t’ (<10.5 MeV)
Et’ = (3/4) × En × Cos2qnt
Plasma serves as both neutron source and target
30
J. Frenje
Simultaneous measurements of the d’ and t’ spectra were
conducted with a simple magnetic spectrometer (CPS2)
Target
CPS2
50keV (p)
2cm
30 MeV (p)
15 MeV (d)
10 MeV (t)
3 MeV (p)
OMEGA-target
chamber
60 laser beams
DD-p spectrum
was also measured
for reference
CR-39:
d’ : 3.7 – 12.5 MeV
t‘ : 2.5 – 10.5 MeV
F.H. Séguin et al., Rev. Sci. Instrum 74, 975 (2003)
31
J. Frenje
d’ and t’ spectra were obtained by selecting signal
and background areas and putting constraints on the
diameters and darkness of the signal tracks
d’
d’-high-energy peak
Bkgd areas
n,2n-p
d’-signal area
t’
Y
t’-signal area
X (energy)
t’-high-energy peak
32
d’
J. Frenje
d’ and t’ spectra were obtained simultaneously
on three OMEGA shots
The n-t differential cross section was obtained by deconvolving the Doppler
broadening and CPS2-response function. The well known n-d differential
cross section was used for absolute normalization of the n-t cross section.
33
J. Frenje
n-d
n-t
NCSM ab-initio
theory3
Faddeev
calculation1
1 E.
Epelbaum et al., PRC 66, 064001 (2002).
2
3
J.A. Frenje et al., PRL 107, 122502 (2011).
P. Navrátil et al., LLNL-TR-423504 (2010).
34
A=5
3H(d,g)5He/3H(d,n)4He
gamma-to-neutron branching ratio
from
Inertial Confinement Fusion
(ICF)
National Ignition Facility (NIF)
Lawrence Livermore National Laboratory
35
National Ignition Facility (NIF)
at LLNL
Inertial Confinement Fusion, 192 laser beams, DT capsule in hohlraum
36
Neutron and g-ray spectrometry typically used to support the
ICF program have been used to explore basic nuclear physics
on NIF (and OMEGA)
MRS (77-324)
nTOF4.5m (64-330)
nTOF3.9m (64-275)
Spec-E (90-174)
NITOF (90-315)
Cross cut image of the NIF chamber
Spec-A (116-316)
M. Gatu Johnson et al., RSI (2012).
F.E Merrill et al., RSI (2012).
37
38
Y. Kim et al.
Phys. Rev. C 85,
061601(R), 2012
New accelerator
driven efforts are
underway
Ohio University
39
A=6
T + T neutron spectrum
from
OMEGA and NIF
40
The T+T reaction has been studied extensively
at OMEGA and NIF
4 μm SiO2
10 atm
DT
10 μm CD
Possible reactions:
12 atm
DT
OMEGA
15 μm CH
17 atm
DT
20 μm CH
17 atm
DT
41
+
T
→
4He
+ 2n (0-9.5 MeV)
T
+
T
→
5He
+ n (8.7 MeV)
T
+
T
→
5He*
+n
Understanding the T+T reaction at low CM
energies has important implications for:
1. Nuclear physics
2. Stellar nucleosynthesis [3He(3He,2p)4He]
3. HEDP/ICF
~230 µm CH
4 atm at 32 K
T2
T
NIF
J. Frenje
Casey measured the T+T neutron spectrum for the first time
using ICF
3.0
n+5He
dN / dE [au]
n+n+4He
Wong (1965)
Allen (1951)
Casey (2012)
2.0
ECM = 250 keV
ECM = 110 keV
1.0
ECM = 23 keV
0
0
5
10
Neutron energy [MeV]
Casey’s measurement was conducted at poor energy resolution,
which washes out a possible weak n+5He resonance (<5%).
15
Casey et al, PRL (2012).
Allen et al, PR (1951).
Wong et al, NP (1965).
42
Casey’s measurement was later improved by high-resolution
measurements of the T+T neutron spectrum at NIF / OMEGA
G. Hale
R-matrix modeling
43
A=12
Nuclear Astrophysics
The 2nd 2+ state in 12C
44
Red giant stars
Resonance enhancement is needed. Nature forms 8Be (ground state is a resonance 92 keV
above the 4He-4He threshold). Helps, but not sufficient. Hoyle (1954) proposed a
resonance in 12C just above the combined mass of 8Be and a-particle. Observed in 1957.
45
Nuclear Astrophysics & EFT Lattice Calculations
A 22+ state in 12C was predicted by
Morinaga (Phys. Rev. 101, 1956) as
the first rotational state of the
“ground” state 7.654 MeV (Hoyle
State)
Hoyle
Recently, Epelbaum, Krebs, Lee,
Meißner (Phys. Rev. Lett. 106,
192501, 2011) have performed Ab
Initio Chiral Effective Field Theory
Lattice calculations for the Hoyle
State and its structure and
rotations.
Epelbaum et al. Phys. Rev. Lett. 109
252501 (2012)
46
Evidence of 2nd 2+ state in 12C
Optical Time Projection Chamber
(OTPC) M. Gai et al.




Gas (Target/Detector) filled volume (CO2+N2)
Grid provides the total energy (E/E of 4 %)
PMTs provide the Time-Projection (10 ns bins): out-of-plane angle of the track
Optical Readout provides the track image: in-plane angle of the track
g + 12C > 3a
47
48
49
50
Evidence of a New 22+ State in 12C: Results
Experiment:
Comparing the Experimental Results and the lattice EFT Calculation
Experiment
Theory
E(22+ - 02+)
B(E2: E(22+ 01+)
2.37 ± 0.11
2.0 ± 1 to 2
0.73 ± 0.13
2±1
51
53
54
Nuclear Astrophysics Impact of the 22+ State
o Helium burning occurs at a temperature of 108–109K, and is
completely governed by the Hoyle state;
o However, during type II supernovae, g-ray bursts and other
astrophysical phenomena, the temperature rises well above
109 K, and higher energy states in
12C
can have a significant
effect on the triple-a reaction rate;
o Preliminary calculations suggest a dependence of high mass
number (>140) abundances on the triple alpha reaction rate
based on the parameters of the 22+ state.
55
Outlook
What’s next at TUNL ?
56
Few-Body Physics Studies at HIGS
o HIGS is currently mounting the GDH experiment on the
deuteron
o Installation of the HIGS Frozen Spin Target (HIFROST) is
ongoing
o The majority of data taking will be completed by the end of
2013 between 4 and 16 MeV
Phys. Rev. C78, 034003 (2008)
Phys. Rev. C77, 044005 (2008)
57
Gerasimov-Drell-Hearn Sum Rule
on the Deuteron

I GDH
2
d P
4

a 2
A
= 
s N    s N   =
NI
2
MN
 thr 
Ip=204.8 b

In=232.5 b

Id=0.652 b
Above pion production threshold: Large positive value
Below pion production threshold: Large negative value
58
Setup for GDH Measurement on Deuteron
Frozen-spin polarized target
HIFROST
59
Compton Scattering
The T-matrix for the Compton scattering of incoming photon of
energy w with a spin (s) ½ target is described by six structure
functions
e = photon polarization, k is the momentum
60
HIGS Results on
16O
and 6Li Compton Scattering
16O
6Li
Phenomenological Model
o Giant Resonances
o Quasi-Deuteron
o Modified Thompson
61
BcPT with  Prediction
a = 10.7 ± 0.7
b = 4.0 ± 0.7
PDG Accepted Value
a = 12.7 ± 0.6
b = 1.9 ± 0.5
62
What’s next elsewhere at low energies?
ICF facilities may play a major role in experimental
Few-Body Physics
63
HIgS2 Layout
e-beam
Laser
beam
-ray
Collaborators: Jun Ye, JILA and
U. of Colorado at Boulder
Mirrors of FP optical cavity
Lcav = 1.679 m
PFB (avg) > 10 kW, 90 MHz
64
What’s new beyond the next 5 years: HIgS2
Comparison of HIgS2 to ELI
ELI: Extreme Light Infrastructure
Bucharest, Prague, Szeged
65
Backup Slides
Nucleon-3He
A=4
elastic scattering
CD Bonn
p-3He
n-3He
INOY04
p-3He
n-3He
p-3H
p-3H
from W. Tornow et al., Phys. Lett. B 702, 121 (2011)
68
The Few-Body System: 4He Inconsistencies !
World Data on
4He(g,n)3He
4He(g,p)3H
References: Raut et al., PRL, 108, 042502 (2012), and Tornow et al., PR C85, 061001R (2012)
The Few-Body System: 4He Results from HIGS
The Few-Body System: 4He Results from HIGS