American Physical Society April meeting press conference schedule

The following press conferences will be offered at the April Meeting of the American Physical Society (APS) in Philadelphia at the Lowe's Philadelphia Hotel (1200 Market Street), where the press operation is located at the Tubman Room. All the press conferences and briefings below will take place in the Anthony Room:

Saturday, April 5, 10:30 AM
CHARGE SYMMETRY BREAKING

In the 1930s, physicist Werner Heisenberg proposed that the neutron and proton are simply slightly different manifestations of the same particle, called the "nucleon." Modern nuclear physics endorses this view: Plenty of nuclear reactions proceed exactly the same way if a proton takes the place of a neutron, or vice versa. However, this close similarity breaks down in some cases, leading to a situation known as "charge symmetry breaking" (CSB). In separate experiments at the Indiana University Cyclotron Facility (IUCF) and TRIUMF in Canada, researchers have made groundbreaking new measurements of CSB (which, incidentally, is a nuclear-physics phenomenon completely different from charge [C] conjugation in particle physics). To be presented by Ed Stephenson of Indiana University ([email protected]) and Allena Opper of Ohio University ([email protected]), such CSB measurements can provide deep insights into why nature gave the neutron and proton slightly different masses. At a more fundamental level, the CSB measurements can shed new light on the differences between the up and down quarks that make up protons and neutrons. According to theorist Jouni Niskanen of the University of Helsinki ([email protected]), the TRIUMF results can provide new constraints on the mass differences between the up and down quarks. Taken together with the proton-neutron mass difference, the new results promise to show us to what extent CSB arises from quark mass differences and the electromagnetic energy that is stored inside the nucleon. (Session C3).

Saturday, 1:30 PM,
THE SHAPE OF THE PROTON

Triggered by state-of-the-art nuclear physics experiments at Virginia's Jefferson Lab (JLab), physicists are now revising some basic assumptions about the proton, one of the "nucleons" that make up the core of an atom. The data are bolstering earlier indications that the proton's quarks carry a substantial amount of orbital angular momentum. Because of this, many nuclear theorists agree on a striking, though little-known point: the proton can have a non-spherical shape, even at relatively low energies, contrary to our textbook notions of the proton as a nice round sphere. Gerald A. Miller of the University of Washington ([email protected]) has developed a model, based on experiment and theory, that shows that the shape of the proton can vary from a pancake to a peanut to a sphere, depending on various values of quark orbital angular momentum and different orientations of quark spin (Paper B3.003). Performing separate calculations based on the Jlab data and the theory of perturbative quantum chromodynamics, theorist Xiangdong Ji of the University of Maryland ([email protected]) draws somewhat different conclusions but still carries the vision of a non-spherical proton. Vina Punjabi ([email protected]), one of the spokespersons on the Jefferson Lab experiments, will provide some commentary on the recent experimental data at that facility.

Saturday, 3:30 PM
ULTRA-HIGH ENERGY COSMIC RAYS

A field currently exciting much interest concerns the observations of ultra-high energy cosmic rays and could imply new physics that we don't yet understand. This is often discussed in terms of the GZK (Greisen-Zatsepin-Kuzmin) limit, an expected upper limit on the energies of cosmic rays due to their interactions with the cosmic microwave background. One experiment (AGASA) indicates the existence of cosmic rays above this limit and physicists are wondering how to explain it. Eli Waxman, Weizmann Institute of Science, Israel, ([email protected]) will claim that the GZK limit remains intact and that more prosaic explanations than the invention of new physics are enough to explain observations. As such, he will argue, somewhat controversially, that the Pierre Auger Observatory under construction in Argentina would be better off searching in an energy range different from that currently planned, to make the best use of resources (Paper F2.003). Representatives of other experiments that observe high-energy cosmic rays (Auger, AGASA and HiRes) will be present to comment.

Sunday, April 6, 9:30 AM
LIGO FIRST RESULTS

Radio, optical, x-ray, infrared, and gamma-ray telescopes look at the universe via electromagnetic waves. For viewing the universe via gravity waves, the most sensitive telescope is the Laser Interferometer Gravitational-Wave Observatory (LIGO), which recently conducted its first full "science" run. The first official results from that run will be announced here. Speakers yet to be named. (Sessions H5 and C5)

Sunday, 2:30 PM
THE DYNAMIC INVISIBLE WORLD OF DARK MATTER

Although we don't know exactly what makes up the dark matter in our universe, simulations are able to show how it should act. Chung-Pei Ma of UC Berkeley, ([email protected]), shows that dark matter is far more dynamics and interesting than we previously thought (Paper H9.001). According to her work with collaborator Ed Bertschinger of MIT, dark matter does not only reside in halos around galaxies as previously thought but co-exists as an invisible universe with satellites and other features we usually see in visible matter. The implications of this work go as far as potentially endangering standard cosmological models. Ma will discuss the latest results and what they could mean for cosmology. Also speaking, Saul Perlmutter of Lawrence Berkeley Lab ([email protected]), will describe the various generations of experiments searching for dark matter and how the latest dark energy data will be influenced by the recently approved SNAP (Supernova/Acceleration Probe) mission (Paper H9.003).

Monday, April 7, 10 AM
FUSION AT THE Z MACHINE

For the first time, Sandia National Laboratories' Z facility has created a hot dense plasma that produces thermonuclear neutrons. The neutrons emanate from fusion reactions within a BB-sized deuterium capsule placed within the central target in the Z facility. Sandia researchers estimate a yield of 10 billion neutrons, corresponding to a very modest level of nuclear fusion (about 4 millijoules of energy). A larger successor to Z, sometime in the future, could attempt to scale up the fusion yield. While the Z approach to nuclear fusion is a promising, straightforward, and potentially robust method, researchers caution that they are at the start of a very long road in investigating its feasibility as a fusion power source. Still, the approach is distinct from other methods. Z caused fusion reactions to occur not by confining plasmas in large magnetic fields, as do tokamaks, or by focusing intense laser beams on or around a target, as in laser fusion, but instead by applying huge pulses of electricity with very sophisticated timing. The pulse creates an intense magnetic field which crushes tungsten wires into a foam cylinder to produce X-rays. Striking the surface of the target capsule embedded in the cylinder, the X-ray energy produces a shock wave that compresses the deuterium within the capsule, fusing enough deuterium to produce neutrons. Sandia's Ray Leeper ([email protected]) will be among the Sandia researchers discussing these results (which will be briefly discussed in talk H6.002). Cornell University's David Hammer ([email protected]) will provide some outside commentary of this exciting milestone for the Z facility.

Monday, 1:15 PM
THE SPEED OF GRAVITY

A beautiful experiment showing gravitational lensing by Jupiter early this year was originally interpreted as providing a measurement of the speed of gravity. However, this view was controversial from the outset. Clifford Will of Washington University, St Louis, ([email protected]) a leading theorist in interpretation of general relativity, will present his analysis of the situation (Paper R12.001). The work will be based on a paper just accepted for publication by the Astrophysical Journal. In it, Will claims that although the experiment is capable of measuring the speed of gravity, the effect is too small to measure and that the value presented as the speed of gravity by Kopeikin and Fomalont is actually the speed of light.

Monday, 1:45 PM
TELESCOPES OF ICE CONSTRAIN NEUTRINO MODELS

Burying string-of-pearl detectors kilometers deep in Antarctic ice does not sound like the usual way to make a telescope. However, that is exactly what is currently happening in the AMANDA neutrino telescope. Steven Barwick, of the University of California, Irvine, ([email protected] ) will report on the latest results from the AMANDA project including data that excludes some previous theoretical models of neutrino generation and provides the best limits on neutrino fluxes from various cosmological sources (Paper P9.006). Barwick will also discuss the upcoming ANITA project that uses Antarctic ice, without anything embedded in it, to form the detector for neutrinos (Paper P9.013). Instead, the impacts of neutrinos are measured by an orbiting satellite looking back down at the ice. The earliest trials of this scheme will be based on high-altitude balloons rather than satellites and are to be launched in December.

OTHER NOTABLE SESSIONS AND RESULTS

THE FUTURE OF PARTICLE PHYSICS, session R15, Monday, April 7, at 2:30 PM, to be held at the University of Pennsylvania campus. Notable speakers include particle physicist Edward Witten (Institute for Advanced Study) and cosmologist Michael Turner (University of Chicago).

THE AIP SCIENCE WRITING AWARD for broadcast stories about physics and astronomy will be presented at a special wine-and-cheese ceremony to NPR reporter David Kestenbaum for his All Things Considered piece, "Misbehaving Muons." Science reporters interested in entering the AIP awards, which encompass print and broadcast media, should visit http://www.aip.org/aip/writing/ (Pressroom, Monday at 5 PM )

THE TOP QUARK IS RESDISCOVERED at Fermilab in a new round of high-energy collisions. No one doubted this outcome, but it is reassuring that after several years of downtime for upgrading the Tevatron machine would once again produce this most rare of the known quarks. Furthermore, scientists at the D0 collaboration have reanalyzed earlier data to arrive at a new value for the mass of the top quark, one that is some 8 billion electron volts higher (paper T13.2).

BEN FRANKLIN as scientist and intellectual force. Session P1 will be held Saturday night, April 5 at the Franklin Institute. The general public is invited to attend. (http://www.fi.edu/)

Reporters who would like to attend the meeting but who have not yet registered should contact Ben Stein at AIP at [email protected]