Department of Particle Physics and Astrophysics

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Michael Hass

Professor Emeritus
Location:Edna and K.B. Weissman Building of Physical Sciences, Room 1104


Current Research Interests

Nuclear structure research has been experiencing an impressive phase of development in recent years, based on ever-growing sophistication and refinements of experimental techniques and theoretical understanding. The main thrust is the quest to study the atomic nucleus for extreme (and ever increasing) values of the proton/neutron ratios, away from presently known nuclei. This endeavor motivates (and is triggered by) the use and construction worldwide of major, modern accelerators for radioactive beams.

This impressive experimental and theoretical development of understanding and probing nuclear structure far from stability has also become very strongly interwoven with the field of nuclear astrophysics - using nuclear physics technique and data for understanding cosmological phenomena. Nuclear structure information is essential in understanding our sun and the solar neutrinos and neutrino masses issues, as well as probing more distant and "exotic" sites that present scenarios for explosive synthesis of heavy elements (such as in x-ray bursts), and others.  We are conducting experiments in facilities both of the "in house" (the Van de Graaff accelerator at the WI) nature, as well as at major International facilities such as ISOLDE (CERN), GANIL (France) and TRIUMF (Canada).

Our most recent activity is in the field trapped radioactive atoms and ions for the study of fundamental interactions and symmetries. For example, detecting beta decay in a trap can probe the minute experimental signal that originates from possible tensor or scalar terms in the weak interaction. Such scalar or tensor terms affect the angular correlation between a neutrino and an electron in the beta-decay process, thus probing new physics of beyond-the-standard-model nature. Traps are mandatory for such experiments since the recoiling nuclei, subsequent to the beta decay, are at sub-keV energies. The current status of Fundamental Interaction studies with Electromagnetic traps and with Magneto Optical Traps is well documented. In this study we present a novel approach – that of using an Electrostatic Ion Beam Trap (EIBT) for these purposes. As an example we focus on the particular case of the β-ν correlation in the decay of 6He.  Of special interest is the newly-constructed 40 MeV, superconducting SARAF accelerator at the Israeli SOREQ Research Centre and the associated R&D work towards production of intense light radioactive beams such as 6He and 8Li that are of interest to nuclear astrophysics as well as to neutrino physics.