E.F. Deveney

How we know that photons are bosons: Experimental tests of spin-statistics for photons

We discuss theoretical models and experimental data that shed light on possible small violations of the spin-statistics relation for photons. Particular emphasis is given to our recent experimental search for non-symmetric photon states, using atomic two-photon transitions.

Production and collisions of neutral beams in the 100 keV to 6 MeV range

High energy beams of neutral atoms can be produced by using electron capture to neutralize an accelerated ion beam. Useful beams of neutral atoms with Z=1 to 6 and squared-velocities up to 0.5 MeV/u have been produced in this manner. The neutral beams may then be used to study a wide variety of processes: electron capture, electron loss from the projectile, ionization of the target, and multiple-electron processes involving both collision partners. Systematics of these processes as functions of energy, projectile charge state, and projectile Z will be discussed.

Novel apparatus and methods for performing remotely controlled particle-solid interaction experiments at CERN

Abstract Recent atomic physics studies involving ultrarelativistic Pb ions required solid target positioners, scintillators, and a sophisticated data acquisition and control system placed in a remote location at the CERN Super Proton Synchrotron near Geneva, Switzerland. The apparatus, installed in a high-radiation zone underground, had to (i) function for months, (ii) automatically respond to failures such as power outages and particle-induced computer upsets, and (iii) communicate with the outside world via a telephone line. The heart of the apparatus developed was an Apple Macintosh-based CAMAC system that answered the telephone and interpreted and executed remote control commands that (i) sensed and set targets, (ii) controlled voltages and discriminator levels for scintillators, (iii) modified data acquisition hardware logic, (iv) reported control information, and (v) automatically synchronized data acquisition to the CERN spill cycle via a modem signal and transmitted experimental data to a remote computer. No problems were experienced using intercontinental telephone connections at 1200 baud. Our successful “virtual laboratory” approach that uses off-the-shelf electronics is generally adaptable to more conventional bench-type experiments.

Non‐statistically populated autoionizing levels of Li‐like carbon: Hidden‐crossings

The intensities of the Auger‐electron lines from autoionizing (AI) states of Li‐like (1s2s2l) configurations excited in ion‐atom collisions vary as functions of the collision parameters such as, for example, the collision velocity. A statistical population of the three‐electron levels is at best incomplete and underscores the intricate dynamical development of the electronic states. We compare several experimental studies to calculations using ‘hidden‐crossing’ techniques to explore some of the details of these Auger‐electron intensity variation phenomena. Our investigations show promising results suggesting that Auger‐electron intensity variations can be used to probe collision dynamics.