1. Discussion Outcomes: Nuclear Astrophysics  Experiments  Equipment/Facility needs  Manpower

2. K. E. Rehm HIgS-II workshop TUNL, June 2, 2013 2 Reactions in nuclear astrophysics (p,  ) (novae, rp-process, big bang) (  ) (red giants) ( ,p) (rp-process) 12 C + 12 C fusion (supernovae) (n,  ) (r-process, s-process) ( ,n) (s-process, red giants) (p,  ) (novae) ( ,p), ( ,n), (  ) (p-process) +  strength function HI ϒ S is one of several tools available for this field.

3. K. E. Rehm HIgS-II workshop TUNL, June 2, 2013 3 1 fb Goal  ( 12 C, 16 O)  The formation of 16 O via the 12 C(  ) 16 O reaction

4. Measuring the 12 C(  ) 16 O via Photodisintegration The Optical Time Projection Chamber (OTPC)  Gas (Target/Detector) filled volume (CO 2 +N 2 )  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  Instead of the capture reaction, measure the inverse reaction 16 O(  ) 12 C. The two cross sections are related by the principle of detailed balance and there is a gain of x40 in the photodisintegration cross section

5. Summary Thoughts on 16 O( γ,α )  Impactful measurements can be done now  Measurements at and below E c.m. =1 MeV benefit tremendously from increased flux  Techniques will be improved iteratively  This physics is not “all or nothing”  Must balance measurements at the lowest energies with high-precision work at higher energies

6. Few-Body Reactions for Big-Bang Nucleosynthesis  D( γ,p)n  3 He( γ,p)D  Can be measured with TPC technique  Driven in part by improvements in D observations  High precision needed: ideally ~2%

7. Equipment / Facility Needs  Vacuum / Bremsstrahlung improvement for bubble chamber measurements  Optical TPC can be upgraded: - longer detector - new scintillator - faster camera system  Beam flux monitor - more dynamic range - absolute calibration  Improved energy resolution with HI γ S2 would benefit many experiments  Data acquisition - accommodate higher data rate - flash ADC

8. Manpower Needs  Data acquisition  Some projects lack local leadership