Investigation of 50Cr(d,n)51Mn and natCr(p,x)51Mn processes with respect to the production of the positron emitter 51Mn

The positron emitter 51Mn (t1/2=46.2 min, Iβ+=97%) is of potential interest in positron emission tomography (PET). With a view to optimizing its production route, excitation functions for deuteron induced nuclear reactions on isotopically enriched (∝95%) 50Cr were determined radiochemically over the energy range of 3 to 13 MeV and for proton induced nuclear reactions on natCr in the range of 18 to 38 MeV. Cross sections are presented for the reactions: 50Cr(d,2n)50mMn, 50Cr(d,n)51Mn, 50Cr(d,t)49Cr, 50Cr(d,p)51Cr, 50Cr(d,α)48V, 52Cr(d,2p)52V, natCr(p,x)51Mn, natCr(p,x)52Mn, natCr(p,x)52mMn, natCr(p,x)54Mn, natCr(p,x)48Cr, natCr(p,x)49Cr, natCr(p,x)51Cr, natCr(p,x)48V and natCr(p,x)45Ti. In the case of proton induced reactions on natCr, the isomeric cross section ratio for the isomeric pair 52m.gMn was also determined. The results are interpreted in terms of the spins of the two isomers concerned. Theoretical thick target yields were derived from the corresponding excitation functions. The maximum achievable thick target yield of 51Mn is 1.1 GBq/μAh in the case of the 50Cr(d,n)51Mn reaction at Ed=14→3 MeV, and 3.2 GBq/μAh in the case of the natCr(p,x)51Mn process for Ep=40→20 MeV. The 50Cr(d,n)51Mn process is the favourable production route for 51Mn, since the radioisotopic purity is high and a small-sized medical cyclotron is adequate to produce this positron emitter in sufficient quantities. (orig.)