Discussion Outcomes:Nuclear Astrophysics

Experiments Equipment/Facility needs Manpower

K. E. Rehm HIgS-II workshop TUNL, June 2, 2013 2

Reactions in nuclear astrophysics

• (p,g) (novae, rp-process, big bang)

• ( ,a g) (red giants)

• (a,p) (rp-process)

• 12C + 12C fusion (supernovae)

• (n,g) (r-process, s-process)

• (a,n) (s-process, red giants)

• (p,a) (novae)

• (g,p), (g,n), ( ,g a) (p-process)

+ g strength functionHIϒS is one of several tools available for this field.

K. E. Rehm HIgS-II workshop TUNL, June 2, 2013 3

1 fb

Goal

a(12C,16O)g

The formation of 16O via the 12C( ,a g)16O reaction

Measuring the 12C( ,a g)16O via Photodisintegration

The Optical Time Projection Chamber (OTPC)

Gas (Target/Detector) filled volume (CO2+N2) Grid provides the total energy (DE/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 16O( ,g a)12C. The two cross sections are related by the principle of detailed balance and there is a gain of x40 in the photodisintegration cross section

Summary Thoughts on 16O(γ,α)

Impactful measurements can be done now Measurements at and below Ec.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

Few-Body Reactions forBig-Bang Nucleosynthesis

D(γ,p)n 3He(γ,p)D Can be measured with TPC technique Driven in part by improvements in D observations High precision needed: ideally ~2%

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 HIγS2would benefit many experiments

Data acquisition- accommodate higher data rate- flash ADC

Manpower Needs

Data acquisition Some projects lack local leadership