Feasibility Study of Short-Lived Beams for Nuclear Physics Research

The development of new types of particle beams is vital to the study of nuclear physics as it can lead to new insights into the structure of the proton, neutron, and the atomic nucleus. Currently there is little existing data of processes induced by short-lived beams. These beams present a problem for analysis as they do not survive long enough to be detected directly. Properties of the short-lived beam particle can be deduced by reconstructing the event from the final-state particles, but the precision of this method must be tested. This research is a proof-of-concept experiment, in which the elastic scattering process pp→pp is measured using data from the CLAS Collaboration at the Thomas Jefferson National Accelerator Facility in Newport News, VA. Using events in which two protons are detected emerging from a liquid hydrogen (proton) target, we tested for the process pp→pp by determining the mass of the incident beam particle using energy and momentum conservation alone. During this run, the particle accelerator produced a photon beam of varying energy; the hypothesized proton beam particle for this measurement was produced within the target by the photon beam. To understand this, we need to know both the number of beam protons produced, and the number of target protons the beam interacted with. The beam flux (beam protons) can be measured directly by performing an analysis in which only a single proton is detected, and counting the number of such events. The target thickness (target protons) can be calculated from the angle of the beam proton. This presentation will present the history and motivation of the short-lived beam project, present the current state of the analysis of the pp→pp elastic scattering process, and suggest future applications of this technique.