News

Nuclear and Particle Physics Colloquium

SPRING 2008

Every Monday
@4:15 pm
Room 26-414, Kolker Room

Refreshments @ 4:00pm

"Dark Matter Direct Detection: the Road to Discovery"

The universe contains at least five times more dark matter than
normal matter, such as atoms. The existence of dark matter is demonstrated by its gravitational interactions, but its fundamental properties are unknown. A world-wide race is on to directly observe dark matter particles interacting in terrestrial detectors. Understanding backgrounds, and distinguishing them from dark matter signals, is the foremost experimental challenge. A novel approach, directional detection, has the potential to make the definitive observation of dark matter using the unique angular signature of the dark matter wind. I will discuss a roadmap to discovery in dark matter direct detection: precision measurements of backgrounds, a unique signal, and new analysis methods to get the most from the data.

"Dark Matter in Bubble Chambers and Changing Fundamental Constants in Ion Traps"

Bubble chambers can be made stable enough for use in rare event searches. I will discuss recent results from the COUPP collaboration, which has used a bubble chamber to obtain the best sensitivity to spin-dependent coupling between protons and intermediate-mass WIMPs (Weakly Interacting Massive Particles). I will also discuss a proposal to search for time-variation of the electron-proton mass ratio by performing high-precision spectroscopy on trapped molecular ions. Time-dependence of this fundamental "constant" is predicted by several extensions of the standard model.

The NSF has recently sited its efforts to establish The Deep Underground Science and Engineering Laboratory (DUSEL) at the former Homestake Mine in Lead South Dakota following a three year examination of possible sites. I will review the status of the progress and process to establish DUSEL and highlight the physics experiments we anticipate to be constructed contemporaneously with the multidisciplinary research facility. Independently of the NSF DUSEL Process, the State of South Dakota is pursuing the creation of an interim laboratory, the Sanford Laboratory, in Homestake. This facility will become operational as early as next year. I will present these efforts and highlight the science program that is being prepared for installation in the Sanford Lab.

"Top Physics & the Large Hadron Collider (LHC)"

We briefly review the road to the top quark discovery.
Then, we describe the important and intriguing role played by the top within the standard model (SM) of elementary particles. We are thus motivated to improve our (rather poor) knowledge of the top fundamental parameter and couplings. It is very exciting that such a study will be possible, very soon,
when the LHC experiment will start running. We demonstrate how the special features of the top quark will allow us to perform precision tests of the SM and open a window to discover beyond the SM physics.

The transition of the quark gluon plasma to stable nuclear matter is
studied in a hundredth of a cubic meter of silicon and wire. How QCD
thermodynamics is simulated on the 600 TeraFlops BlueGene/L
supercomputer and how the machine was built and programmed: the
results of today and the acid tests of tomorrow.

"The astroparticle frontier: recent results from the Pierre Auger Cosmic Ray Observatory"

Arrival directions of the highest energy cosmic rays are correlated with positions of nearby Active Galactic Nuclei. Potential implications may include the following: (1) High energy cosmic rays are accelerated in discrete extragalactic sources. (2) Pion photoproduction causes the observed drop in the cosmic ray energy spectrum near 10 Joules/particle. (3) Intergalactic magnetic fields are not strong, nor are the fields in the halo of our Galaxy. (4) With a bigger collecting area, the Auger Observatory will open a new window of charged particle astronomy. (5) The primary particles are protons, not larger nuclei. (6) Measured properties of the air showers produced by these protons challenge the extrapolation of hadronic interaction models to 300 TeV center-of-mass energy.

Big Bang Nucleosynthesis (BBN) is a key pillar of modern cosmology, providing a probe of the particle content and expansion rate of the Universe a mere few minutes after the beginning. The observationally inferred primordial abundances of Deuterium and Helium-4, when compared to the BBN predictions, provide an excellent baryometer and chronometer, respectively. Helium-4 is sensitive to the neutrino content of the Universe and is a window onto any asymmetry between neutrinos and antineutrinos and, a probe of the early Universe expansion rate. On the other hand, the spectrum of temperature fluctuations imprinted on the Cosmic Microwave Background radiation (CMB), is sensitive to the baryon density and to the expansion rate some 400 thousand years later in the evolution of the Universe. The complementary constraints imposed by BBN and the CMB are reviewed, revealing a consistent picture of the Universe at two very widely separated epochs, leading to new, tighter constraints on the baryon density at present and on possible new physics beyond the standard models of particle physics and cosmology.

Borexino is a large liquid scintillation detector designed to observe solar neutrinos with energies below 1 MeV. It is located in the Gran Sasso underground laboratory in Italy and has a shielded sensitive mass of 100 ton. The main goal of the experiment is to measure the rate of 0.862 MeV 7Be neutrinos, expected to be ~ 75 events per day without neutrino oscillations. Neutrino oscillations are expected to reduce the rate to about 50% of this value. The detector became operational in May 2007 and first data, published in October 2007, revealed a remarkably low background. The detector has been acquiring data for a year and results based the first full year will be published soon. I will discuss the first results and the potential scientific reach of the experiment, as well as summarize methods developed to overcome the most serious background problems due to natural radioactivity. I will conclude by commenting on other applications of the low background methods that were developed for Borexino.

Gabriella Sciolla (Chair)
Joseph Formaggio
Bernd Surrow
John Negele
Alan Guth
Harvey Meyer



		Nuclear and Particle Physics Colloquium SPRING 2008 Every Monday @4:15 pm Room 26-414, Kolker Room Refreshments @ 4:00pm February 11th Jocelyn Monroe, MIT "Dark Matter Direct Detection: the Road to Discovery" The universe contains at least five times more dark matter than normal matter, such as atoms. The existence of dark matter is demonstrated by its gravitational interactions, but its fundamental properties are unknown. A world-wide race is on to directly observe dark matter particles interacting in terrestrial detectors. Understanding backgrounds, and distinguishing them from dark matter signals, is the foremost experimental challenge. A novel approach, directional detection, has the potential to make the definitive observation of dark matter using the unique angular signature of the dark matter wind. I will discuss a roadmap to discovery in dark matter direct detection: precision measurements of backgrounds, a unique signal, and new analysis methods to get the most from the data. February 18th PRESIDENTS' DAY February 25th Brian Odom, University of Chicago "Dark Matter in Bubble Chambers and Changing Fundamental Constants in Ion Traps" Bubble chambers can be made stable enough for use in rare event searches. I will discuss recent results from the COUPP collaboration, which has used a bubble chamber to obtain the best sensitivity to spin-dependent coupling between protons and intermediate-mass WIMPs (Weakly Interacting Massive Particles). I will also discuss a proposal to search for time-variation of the electron-proton mass ratio by performing high-precision spectroscopy on trapped molecular ions. Time-dependence of this fundamental "constant" is predicted by several extensions of the standard model. March 3rd PAPPALARDO ROOM, 4-349 Ernie Moniz, MIT "The Energy-Environment Challenge and MIT's Energy Initiative" March 10th Kevin Lesko, LBL "Deep Underground Science and Engineering Laboratory at Homestake" The NSF has recently sited its efforts to establish The Deep Underground Science and Engineering Laboratory (DUSEL) at the former Homestake Mine in Lead South Dakota following a three year examination of possible sites. I will review the status of the progress and process to establish DUSEL and highlight the physics experiments we anticipate to be constructed contemporaneously with the multidisciplinary research facility. Independently of the NSF DUSEL Process, the State of South Dakota is pursuing the creation of an interim laboratory, the Sanford Laboratory, in Homestake. This facility will become operational as early as next year. I will present these efforts and highlight the science program that is being prepared for installation in the Sanford Lab. March 17th Gilad Perez, Stonybrook "Top Physics & the Large Hadron Collider (LHC)" We briefly review the road to the top quark discovery. Then, we describe the important and intriguing role played by the top within the standard model (SM) of elementary particles. We are thus motivated to improve our (rather poor) knowledge of the top fundamental parameter and couplings. It is very exciting that such a study will be possible, very soon, when the LHC experiment will start running. We demonstrate how the special features of the top quark will allow us to perform precision tests of the SM and open a window to discover beyond the SM physics. March 24th SPRING BREAK March 31st Pavlos Vranas, LLNL "The Quark and the Supercomputer" The transition of the quark gluon plasma to stable nuclear matter is studied in a hundredth of a cubic meter of silicon and wire. How QCD thermodynamics is simulated on the 600 TeraFlops BlueGene/L supercomputer and how the machine was built and programmed: the results of today and the acid tests of tomorrow. April 7th Matthias Burkardt, New Mexico State University "Hadron Tomography" TUESDAY, APRIL 15th - talk begins at 4PM JOINT ASTRO-LNS COLLOQUIUM - Marlar Lounge, 37-252 Paul Sommers, Penn State "The astroparticle frontier: recent results from the Pierre Auger Cosmic Ray Observatory" Arrival directions of the highest energy cosmic rays are correlated with positions of nearby Active Galactic Nuclei. Potential implications may include the following: (1) High energy cosmic rays are accelerated in discrete extragalactic sources. (2) Pion photoproduction causes the observed drop in the cosmic ray energy spectrum near 10 Joules/particle. (3) Intergalactic magnetic fields are not strong, nor are the fields in the halo of our Galaxy. (4) With a bigger collecting area, the Auger Observatory will open a new window of charged particle astronomy. (5) The primary particles are protons, not larger nuclei. (6) Measured properties of the air showers produced by these protons challenge the extrapolation of hadronic interaction models to 300 TeV center-of-mass energy. April 21st PATRIOT'S DAY TUESDAY, April 29th - talk begins at 4PM JOINT ASTRO-LNS COLLOQUIUM - Marlar Lounge, 37-252 Gary Steigman, OHIO STATE UNIVERSITY COSMOLOGICAL NUCLEOSYNTHESIS Big Bang Nucleosynthesis (BBN) is a key pillar of modern cosmology, providing a probe of the particle content and expansion rate of the Universe a mere few minutes after the beginning. The observationally inferred primordial abundances of Deuterium and Helium-4, when compared to the BBN predictions, provide an excellent baryometer and chronometer, respectively. Helium-4 is sensitive to the neutrino content of the Universe and is a window onto any asymmetry between neutrinos and antineutrinos and, a probe of the early Universe expansion rate. On the other hand, the spectrum of temperature fluctuations imprinted on the Cosmic Microwave Background radiation (CMB), is sensitive to the baryon density and to the expansion rate some 400 thousand years later in the evolution of the Universe. The complementary constraints imposed by BBN and the CMB are reviewed, revealing a consistent picture of the Universe at two very widely separated epochs, leading to new, tighter constraints on the baryon density at present and on possible new physics beyond the standard models of particle physics and cosmology. May 5th Dima Kharzeev, BNL "Quantum anomalies and bulk properties of hot QCD matter" May 12th Frank Calaprice, Princeton University "First Results from the Borexino Solar Neutrino Experiment" Borexino is a large liquid scintillation detector designed to observe solar neutrinos with energies below 1 MeV. It is located in the Gran Sasso underground laboratory in Italy and has a shielded sensitive mass of 100 ton. The main goal of the experiment is to measure the rate of 0.862 MeV 7Be neutrinos, expected to be ~ 75 events per day without neutrino oscillations. Neutrino oscillations are expected to reduce the rate to about 50% of this value. The detector became operational in May 2007 and first data, published in October 2007, revealed a remarkably low background. The detector has been acquiring data for a year and results based the first full year will be published soon. I will discuss the first results and the potential scientific reach of the experiment, as well as summarize methods developed to overcome the most serious background problems due to natural radioactivity. I will conclude by commenting on other applications of the low background methods that were developed for Borexino. Committee Members: Gabriella Sciolla (Chair) Joseph Formaggio Bernd Surrow John Negele Alan Guth Harvey Meyer
updated 5/7/08