Nuclear Physics

Juan Collar

See Prof. Collar's entry under Observational Astrophysics & Cosmology.

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Zheng-Tian Lu

See Prof. Lu's entry under Experimental Atomic Physics.

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Guy Guy Savard

Ph.D., McGill, 1988.
Senior Scientist, Physics Division, Argonne National Laboratory.
Professor (part time), Dept. of Physics, Enrico Fermi Institute.
Experimental physics, nuclear physics.

My current research is centered around low-energy tests of the Standard Model of electroweak interaction. These studies are performed on samples of radioactive ions captured in ion traps where they are available for high-precision experiments. New techniques developed by our group to efficiently capture short-lived isotopes of essentially any species in ion trap allow us to select isotopes with decay properties which enhance and isolate specific effects and hence increase our sensitivity to the physics of interest. The present experimental program is looking at a more precise determination of the weak vector coupling constant and a more precise test of CVC and the unitarity of the Cabibbo-Kobayashi-Maskawa matrix. A related experiment currently in preparation will search for scalar currents outside the standard V-A form for the charged electroweak interaction using samples of trapped superallowed emitters.

The type of experiment I am performing would greatly benefit from a more intense and versatile source of radioactive ions, and such a source has been assessed a high priority for new construction in nuclear physics in the US. I am therefore also heavily involved in the R&D for such a facility, which will use a novel technical approach for the fast extraction of the radioactive species based on some of the technologies we developed for ion trapping. (The leading contender for this facility is Argonne National Laboratory, located a short distance from Chicago.) More information on the proposed radioactive beam facility (RIA).

Selected Publications:

  • Precise Half-life Measurement for the Superallowed 0+ to 0+ beta-emitter 74Rb: First Results from ISAC, the New Radioactive Beam Facility at TRIUMF. G.C. Ball et al. Phys. Rev. Lett. 86, 1454, 2001.
  • Precision Nuclear Measurements with Ion Traps. G. Savard and G. Werth. Ann. Rev. of Nucl. and Part. Sci. 50, 119, 2000.
  • High-Accuracy Mass Determination of Cesium and Barium Isotopes. F. Ames et al. Nucl. Phys. A651, 3, 1999.
  • Weak Interaction Studies with an On-line Penning Trap Mass Spectrometer. G. Savard et al. Nucl. Phys. A654, 961c, 1999.
  • Beta+ Decay Partial Half-Life of 54Mn and Cosmic Ray Chronometry. A.H. Wuosmaa et al. Phys. Rev. Lett. 80, 2085, 1998.
  • Ion trap technology at accelerator facilities. G. Savard. Nucl. Instr. & Meth. B126, 361, 1997.
  • Pionic fusion of heavy ions. D. Horn et al. Phys. Rev. Lett. 77, 2408, 1996.
  • 10C superallowed branching ratio and the Cabibbo-Kobayashi-Maskawa matrix unitarity. G. Savard et al. Phys. Rev. Lett. 74, 1521, 1995.

Related Links:

Updated 5/2001

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Schiffer John P. Schiffer

Ph.D., Yale, 1954.
Senior Physicist, Physics Division, Argonne National Laboratory.
Professor Emeritus, Dept. of Physics, Enrico Fermi Institute.
Experimental physics, nuclear physics.

My primary interests are in trying to understand the single-particle structure and effective interactions that underlie the structure of atomic nuclei. This entails calibrating reaction mechanisms to best extract the relevant information. Some of this work was done a long time ago - and some recently - particularly with a focus on how these nuclear properties might change as nuclei move further away from stability.

I have had a continuing interest in exotic particles in nature [2], and in trying to confirm or debunk exotic phenomena [6].

I am currently involved with measurements related to exotic and poorly studied short-lived nuclei that are of interest both for the empirical nuclear structure, the underlying theory, and for reactions in hot stars [4,10]. I have proposed a new scheme for charged-particle detection from reactions in inverse kinematics (that is required with radioactive beams) a technique that effectively overcomes many of the current difficulties encountered in such measurements [9]. The scheme requires a large super-conducting solenoid which has been constructed and is in use. A program of re-measuring single-particle structure carefully in stable nuclei to provide a better anchor point for the most exotic regime is being carried out [3,8].

A related endeavor is to try and characterize the nuclei that are used in searches for neutrinoless double beta decay. If (when) this process is observed it would prove that neutrinos are their own antiparticles. But the rate for this process would also provide a unique handle on the neutrino mass, if the matrix elements for the nuclear decay are known. The theoretical calculations for these matrix elements is not in good shape and the objective of these experiments is to constrain them with the measurement of the relevant nuclear properties [7,11].

An interest that grew out of nuclear physics is in the simulation of very cold plasmas such as can be obtained in ion traps and storage rings and the properties of such plasmas properties associated with crystallization [1].

Selected Publications:

  1. Melting of crystalline confined plasmas, J. P. Schiffer, Phys. Rev. Lett. 88, 205003 (2002).
  2. Search for anomalously heavy isotopes of helium in the Earth’s Atmosphere, P. Mueller et al., Phys. Rev. Lett. 92, 022501 (2004).
  3. Is the nuclear spin-orbit interaction changing with Neutron Excess?, J. P. Schiffer et al., Phys. Rev. Lett. 92, 162501 (2004).
  4. Laser spectroscopic determination of the 6He charge radius, L.-B. Wang et al., Phys. Rev. Lett. 93, 142501 (2004).
  5. A solenoidal spectrometer for reactions in inverse kinematics, A. H. Wuosmaa et al., Nucl. Instr. and Meth. 580, 1290 (2007).
  6. Search for x-ray induced decay of isomeric 178Hf with synchrotron radiation, I. Ahmad et al., Phys. Rev. C 71, 024311 (2005).
  7. Nuclear Structure and Neutrinoless Double β Decay: 76Ge and 76Se, J.P. Schiffer et al. Phys. Rev. Lett. 100, 112501 (2008).
  8. High-j Single-Particle Neutron States Outside the N = 82 Core, B. P. Kay et al. Phys. Lett. B 658, 216 (2008).
  9. First Experiment with Helios: the Structure of 13B, B. B. Back, et al. Phys. Rev. Lett. 104, 132501 (2010).
  10. 15C(d,p)16C Reaction and the Exotic Behavior of 16C, A. H. Wuosmaa et al. Phys. Rev. Lett. 105, 132501 (2010).
  11. Pair Correlations and Neutrinoless Double β Decay of 130Te, T. Bloxham et al. Phys. Rev. C 82, 027308 (2010).

Updated 2/2011

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