Studies of range and straggling of muons in metals by the projected range imaging (PRI) technique

A new mu SR method for directly imaging the implantation depth distribution of positive muons in metals (Projected Range Imaging: PRI) is presented an d the results obtained from several experiments are reported. Strong magnet ic field gradients inside a metallic film are produced by driving an electr ic current in it: spin polarized muons stopped in the film have Larmor prec ession frequencies proportional to the implantation depth. Generation of fi eld gradients, advantages and features of the method are discussed. For muo n energy in the MeV range the results are compared with Monte Carlo simulat ions and with experimental results obtained by using the conventional moder ator curve method. Applications to range and straggling studies with epithe rmal muons are also envisaged. These future extensions will allow a better understanding of the energy loss mechanisms in the previously inaccessible very low energy range. (C) 1999 Elsevier Science B.V. All rights reserved.