Doubly differential emission distributions for electron loss to the continuum from fast heavy projectiles in gas targets

Abstract

We have constructed an apparatus which utilizes position-sensitive detector technology for the measurement of doubly differential electron emission cross-sections in ion-atom and ion solid collisions at emission angles near the forward direction. The properties of the instrument make it especially well suited for the simultaneous doubly differential measurement of electron emission processes which are centered in the frame of the projectile, and so it is of value for investigations of the well known electron capture and loss to projectile-centered continuum state processes (ECC and ELC) which have received much attention at this symposium. Further, the multichannel nature of the system leads to improved data acquisition efficiency, sometimes an important advantage for the observation of processes which require the use of heavily-subscribed accelerator user facilities. We describe here results of some of the first measurements to be made with this apparatus, specifically for the doubly differential (in velocity and angle) cross s~tion (DDCS) for continuum transfer emission from collisions of 41, 82, and 105 MeV O ~ in helium and argon gas targets. Because the projectiles carry a relatively loosely bound 2s electron into the collision, ELC processes are expected to dominate the emission characteristics.