סמינר ארצי בפיזיקה גרעינית

First talk at 14.30:

Atom Trap, Krypton-81, and Global Groundwater

Lecturer: Zheng-Tian Lu, Argonne National Laboratory

Abstract:

Abstract: The long-lived noble-gas isotope 81Kr is the ideal tracer for old water and ice in the age range of 105 - 106 years, a range beyond the reach of 14C. 81Kr-dating, a concept pursued over the past four decades by numerous laboratories employing a variety of techniques, is now available for the first time to the earth science community at large. This is made possible by the development of an atom counter based on the Atom Trap Trace Analysis (ATTA) method, in which individual atoms of the desired isotope are selectively captured and detected with a laser-based atom trap. ATTA possesses superior selectivity, and is thus far used to analyze the environmental radioactive isotopes 81Kr, 85Kr, and 39Ar. These three isotopes have extremely low isotopic abundances in the range of 10-16 to 10-11, and cover a wide range of ages and applications.In collaboration with earth scientists, we are dating groundwater and mapping its flow in major aquifers around the world.

Second talk at 15:55:

Experimental evaluation of the nuclear neutron–proton contact

Lecturer: Nir Barnea, Hebrew University

Abstract:

Abstract: The nuclear neutron-proton contact is introduced, generalizing Tan's work, and evaluated from medium energy nuclear photodisintegration experiments. To this end we reformulate the quasi-deuteron model of nuclear photodisintegration and establish the bridge between the Levinger constant and the contact. Using experimental evaluations of Levinger's constant we extract the value of the neutron-proton contact in finite nuclei and in symmetric nuclear matter. Assuming isospin symmetry we propose to evaluate the neutron-neutron contact through measurement of photonuclear spin correlated neutron-proton pairs.

מארגן הסמינר: פרופ' אלי פיסצקי