Trends in the kinematics for transfer

To study transfer reactions with radioactive beams, it is necessary to use inverse kinematics. The simplest transfer reactions to attempt in the first instance are those induced by light particles as mentioned above: for example, ¹H and ²H nuclei. If `heavy ion' targets were used, then an example would be <sup>13</sup>C for neutron transfer. Considering the hydrogen targets first, there is a general property of the kinematics depending on whether a `pickup' reaction such as (p,d) or a `stripping' reaction such as (d,p) is employed. In cases such as (p,d), the light particle tends to be confined to the forward hemisphere in the laboratory frame. In contrast, for reactions such as (d,p) the light products tend to be concentrated in the backward hemisphere. Example calculations are presented for a selection of (p,d), (d,p) and (d,<sup>3</sup>He) reactions, in section 10 of this technical document. For reactions using the `heavy ion' targets, the target-like reaction products of interest tend to be emitted near 90 degrees in the laboratory. An example calculation is given for a reaction on ¹³C in section 10. In each case, the precise angular range of interest depends crucially on the reaction Q-value, so it is not possible to give hard limits for the angular ranges to be covered for each kind of reaction. Experience has shown that there is some scope in an individual experiment to adjust other experimental parameters in order to work within a specified angular range, but this is limited. Thus, in some experiments using p and d targets the annular detectors will cover sufficient of the angular range for the transfer experiment, but in others the Q-value and masses will conspire to spread the reaction products over a wider range of angles. For this reason, the barrel part of the array is important for studying reactions on light target nuclei, as well as for studying reactions on heavier targets as already mentioned. In addition, the barrel makes it possible to design experiments to study several different transfer channels simultaneously, regardless of their different detailed kinematic focussing properties.