The determination of the l-forbidden M1 decay from the first excited state in41K

Abstract
The reactions 38Ar( alpha ,p)41K, 41K(p,p')41K and 44Cu(p, alpha )41K have been used to resolve the conflict over the lifetime of the first excited state in 41K. A value of tau m=5.0+or-1.5 ps was found to be consistent with the data. The Couloumb excitation of 41K with an 16O beam was used to measure the E2 excitation probability B(E2)=1.4+or-0.2 Wu for the first excited state and allowed the deduction of the multipole mixing ratio delta and hence the M1 decay component of this transition. A result of B(M1)=6+or-2 mWu was obtained.