22 Ne( α , γ /n)

1. 22Ne(α, γ/n) • 22Ne(α, n)25Mg reaction is the main source of neutrons for s-process • - there is competition from the 22Ne(α, γ)26Mg reaction • - s-process is the origin of nuclides heavier than iron • The α-particle and neutron threshold are: Sα = 10.615 MeV andSn= 11.093 MeV • - many of the states in this energy range (and a little higher energy) have uncertain energies and quantum number, which are important ingredients for rate calculations • According to Endtet al., there are 21 levels between Sα and Snthresholds, most of which have unknown energies and quantum numbers • α and 22Ne have spin and parity of 0+, hence they tend to populate natural parity states: • 0+, 1-, 2+, 3-, 4+, …

2. 22Ne(α, γ/n) • Some previous experiments include: • α- particle transfer: 22Ne(6Li,d)26Mg by CladioUgaldeet al. • photoexcitation: 26Mg(γ, γ’) 26Mg by Longlandet al. • neutron capture: 25Mg(n, γ) 26Mg by Koehler • We intend to conduct the direct reaction of • 22Ne(α,n)25Mg and 22Ne(α,γ)26Mg • 22Ne(α,x) has Coulomb barrier of 0.229 MeV • To conduct this experiment, we need the accelerator to be stable at ~ 820 keV • - this is about 11.3 MeV excitation energy