(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.

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

3,4He 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

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

Optical TPC - Active Target Measure 16O(g,a 12C) in Optical TPC Chamber (Ec.m.=1.4 -2.2 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)

16O(g,a 12C) in Optical TPC flux >1x107 , DE/E beam~0.5% ECM Eg(MeV) Y(cpd) Time(10%) 2.2 9.4 630 10 hrs 2.0 9.2 240 20 hrs 1.8 9.0 81 50 hrs 1.6 8.8 33 200 hrs 1.4 8.6 12 300 hrs

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

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