1. (g,z) Breakup Experiments Charged Particles in the Final State
Few-body Studies
Further high precision work of few-body systems is necessary for resolving issues with many-body forces.
Nuclear Astrophysics Cross Sections
Many Astrophysically important cross sections appear to be at their limits with traditional direct measurement techniques.
New techniques using exclusive triggers (LENA) or deep underground shielding (LUNA) may push measurements forward.
Indirect: Virtual Photons – Coulomb Dissociation
HIGS with real mono-energetic photons can contribute.

2. Challenges for (g,CP) Breakup Experiments
Issues – Reaction products face dE/dX in the target
"thick" targets are not reasonable
– Product energies decrease near Ethreshold
difficult to detect particles
– Backgrounds: targets impurities/environment
Targetry & Detectors
- Active Targets (self contained experiment/gas chamber)
- Passive targets surrounded by Charged-Particle detectors

3. 3,4He gas scintillator targets to study two-body breakup
Measured s(g + 3He ad+p)
Cell with 35 Atm. 3He
Detector: REU Cara Campbell
Thesis data of J. Esterline (Tornow)
Propose to carry on work in 2-body 4He subsystems
g + 4He a p+t, n+3He, (d+d), 3-body breakup ... d p
Pulse Height

4. 12C(a,g)16O reaction a persistent astrophysics problem
- Already 7 12C(a,g) publications in 2005
- How can we contribute to 12C(a,g)16O measurements?
12C(a,g)16O determines the 12C/16O ratio in a star, the formation of heavier elements within the star, and can determine the fate of a star (carbon-rich: neutron star or oxygen-rich: black hole ) for Type II Supernovae.
Dryer and Barnes NPA233 (74) 495
Redder NPA462 (87) 385

5. Optical TPC - Active Target
Measure 16O(g,a 12C) in Optical TPC Chamber (Ec.m.= MeV)
(100 mbar) CO2 + triethylamine (C6H15N)
35 cm active length – areal densities of
>2x1020 O/cm2 (energy independent)
Breakup reaction observables
recoil energies determined 5%
4p coverage with 12C and a tracking
reaction position determined – few mm
breakup angle determined ~1-deg
determines E1 and E2 components
UConn, Weizmann Institute, Georgia College & State University, TUNL ... (PI Moshe Gai)

6. 16O(g,a 12C) in Optical TPC flux >1x107 , DE/E beam~0.5%
ECM Eg(MeV) Y(cpd) Time(10%)
hrs
hrs
hrs
hrs
hrs

7. CHArged Particle Si-Strip array (CHAPSS) Traditional approach – surround a target with detectors
Any solid target is feasible
Test-run on SiO2 (16O breakup): 1 shift
16O: Ex=13.1 MeV, G=130 KeV, s = 6.4 mb
1 cm collimator: 3 x 105 g/s: ~15 counts/hour
sizeable environmental background d
Effective
Thickness
Interpretation of the data is complex:
Effective target is thin and at the surface (thickness is Eg dependent)
Eejectile=Emax – 0 (depending on depth of reaction, Eg and Q-value)
multiple scattering
requires Monte Carlo modeling

8. Future Directions in (g,CP) reactions
Further Studies relevant to Nuclear Astrophysics
Determination of branching ratios for unbound states
Photo-excitation of target nuclei into particle-unbound states
Nuclear level spectroscopy
Very high excitation continuum that populates the resonances of the daughter, i.e. Boland 7Li(g,p)6He (50-70 MeV g rays)
Monoenergetic g-ray beam is a plus
Boland PRC 64 (2001) 31601