Nuclear Astrophysics with the PJ Woods, University of Edinburgh

Puzzle of the origin of heavy ‘p-nuclei’ – abundant proton-rich isotopes eg 92 Mo and 96 Ru Supernova shock passing through O-Ne layers of progenitor star

Predicted p-process abundances relative to observed abundances Arnould & Goriely Phys. Rep. 384,1 (2003)

Study of 96 Ru(p,γ) 97 Nb reaction with decelerated beams on ESR using DSSD system for recoil detection (GSI, Frankfurt,Edinburgh) Reaction peak observed! σ(p,γ)= 3.6(5) mb

Measurements of (p,  ) or (α,  ) rates in Gamow window for the astrophysical p-process using inverse kinematics. Advantages of ring approach: Applicable to radioactive nuclei Detection of ions via in-ring particle detectors (low background, high efficiency) Measurements of (p,n) reactions also possible Gas jet Particle detectors  New DSSD system being jointly developed by Edinburgh GSI and Frankfurt for use in UHV for measuring reactions in centre of Gamow burning energy region.

Application of p-process method to Advantages: RIBs can be injected into TSR at appropriate energy and do not need time consuming deceleration phase  loss of beam intensity due to radiaoctive decay RIBs when injected from HIE-ISOLDE will already have good beam quality characteristics  less cooling time required in ring Challenge: To produce fully stripped ions of relatively high Z(>30-70<)  High electron capture stripping reaction cross-section will swamp recoil detector and reduce beam lifetime

Galactic abundance distribution of the cosmic γ-ray emitter 26 Al INTEGRAL Measured abundance 2.8(8) Solar Masses [R. Diehl, Nature 439, 45(2006)]

Presolar grains Andrew M Davis. University of Chicago o Grains are found to have a high 26 Mg/ 24 Mg abundance ratio thought to reflect injection of 26 Al material which subsequently β-decays

Supernova Cycle

Mg-Al Cycle MgMgMg AlAlAl SiSiSi MeV 1Myr 6s Hydrogen burning in Mg – Al Cycle

 Next stage to estimate resonance strengths  Use transfer reactions to determine Г p for (p,γ) reactions  New high resolution study performed of the d( 26g Al,p) 27 Al analogue reaction using the Edinburgh group’s TUDA silicon strip detector array on the ISAC II facility at Triumf (June 2012) NB exotic reaction since 26g Al has J π = 5 + !

d( 26g Al,p) 27 Al study using G. Lotay, PJW et al. 0  increasing excitation energy Astrophysically Important Region

7175 9/ / / / / / / / /2 − /2 +

In-ring target chamber & heavy-ion recoil detection system in UHV Indirect Studies of Key Astrophysical Resonances e.g. d( 26m Al, p) 27 Al destruction of 26 Al in core collapse supernovae - meteoritic abundances

Transfer reaction studies of astrophysical resonances on the High resolution studies possible with high quality RIBs  vital for resolution of key resonance in regions of high level density, E x ~ 6-8 MeV Ions injected at perfect energy for transfer ~6 MeV/u Most important reactions have relatively low Z ions, relatively close to stability  intense fully stripped RIBs with long lifetimes use of isomeric beams eg 26m Al no background from reactions on target impurities eg Carbon from (CH 2 ) n

The 15 O( ,  ) 19 Ne reaction: the nuclear trigger of X-ray bursts Reaction regulates flow between the hot CNO cycles and rp process  critical for explanation of amplitude and periodicity of bursts

Γ α /Γ ≈ Rate dominated by a single 3/2 + resonance at 504 keV Key experimental uncertainty, alpha branching ratio

First transfer reaction measurement at the ESR data evaluation under way P. Woods et al. AP MeV 1/2- state in 19 Ne MeV 3/2+ state in 19 Ne Experiment: October Ne(p,d) 19 Ne reaction Ne 50 MeV/u H 2 /cm 2 gas target Electron cooler ESR Online data

Summary and Forward Look Exciting new developments in explosive nuclear astrophysics will be opened up by Transfer reaction studies of nuclear astrophysical resonances will require development of high resolution, high efficiency silicon strip detector system(s) operating in UHV conditions around target. p-process radiative capture studies will require development of fully stripped high Z ions, and forward angle heavy ion recoil detector system in region of 1 st TSR dipole. Thought will need to be given to the transfer of expertise for development of thick gas jet targets ~ atoms/cm 2

Beam parameters