An investigation of the components of the neutral beam produced by high energy protons at NAL using the 30 inch bubble chamber

Abstract

We wish to search for new neutral particles by investigating the composition of a wide angle neutral beam produced by high energy protons on a Be target. Photons in the beam will be removed by a Pb converter.The resultant neutral beam will be incident on the 30" bubble Chamber.The composition of the beam will be detennined from the kinematic analysis of selected interactions in the bubble chamber, through the decays of neutral particles and through possible anomalies in the hydrogen inter actions. As a byproduct we will measure the Ki. flux through the process Ki. + P + KS + all. By a slight change in the geometry we can look at a region immediately downstream of the target and measure the characteristics of neutral particles arising from the decay of hyperons and other particles produced in the Be target. We do not require any external equipment besides beam monitoring equipment. We request an initial exposure of 20,000 pictures.One of the most exciting possibilities for discovery opened up by the high energy proton beam at NAL is the possibility of new particles pro duction. Many experiments have already been proposed to search for new charged particles (quarks, Wmesons, etc.). We wish to search for the production of new neutral particles. A new particle can be isolated in one of three ways 1. Measure the charge and mass with various spectrometers.2. Decays into simple final states and kinematic fitting to determine the neutral particle mass.3. Through the characteristics and kinematics of the inter actions with protons.Method 1 is clearly not useful for neutral particles. Method 2 was extraordinarily useful in establishing the low mass hyperons and KO mesons.However, for high mass objects mu1tipartic1e decay might make it difficult to separate these objects from KO or hyperon decays. Method three is perhaps the most promising provided that (a) the neutral particles inter act with similar cross sections to neutrons and KO mesons, (b) the new neutral particles interact producing characteristically different final states or producing low multiplicity final states allowing a kinematic fi t to deduce the neutral particle mass. For methods 2 and 3 the bubble chamber is very well suited and 3 requires a hydrogen bubble chamber. If new neutral particles are produced strongly we expect them to interact with approximately the same strength as the strong interactions. The same would be true of neutral quark like objects. The detection of new weakly inter acting particles requires massive detectors unless they decay with a life time between 10-7 -10-6 sec. z There is little theoretical rational for searching for new neutral particles but of course there was also no theoretical reason for searching for A hyperons or KO mesons or the neutron for that matter. We note that there have been from time to time some discussion of anamolies in the interaction or production of neutral particles in the cosmic radiation with nuclear emulsions which might be ascribed to new neutral particles.l,z It is therefore our goal to pr...