The U. Maryland Particle Astrophysics group has key leadership responsibilities on two of the major experimental efforts in the field: IceCube and Milagro. The IceCube Observatory is currently in the midst of a successful construction project at the Antarctic South Pole through an NSF Major Research Equipment and Facilities Construction award. The IceCube detector has currently deployed 22 strings and by the start of this grant proposal period IceCube will have more than half the volume instrumented and be approaching one cubic kilometer-year of accumulated data. The observation of high-energy neutrinos from distant astrophysical sources will open a new window on the sky and will provide new information on the acceleration mechanisms at work in these objects and insight into the nature of cosmic radiation.
This proposal requests funds for the Maryland group to pursue the following physics goals with the IceCube detector for which they have had a major part in building: 1) search for astrophysical point sources of neutrinos using muons in IceCube, 2) search for Weakly Interacting Massive Particles using muon neutrinos in IceCube, 3) search for neutrinos coincident with gamma-ray bursts, 4) search for exotic particles such as monopoles and 5) search for high energy diffuse neutrinos of astrophysical origin.
Milagro has demonstrated that a water-Cherenkov shower detector is a powerful tool for looking at the TeV sky. Their survey of the galaxy revealed both new TeV sources (at least one with a spectrum extending to ~100 TeV) and strong diffuse emission. While detector operations will end this year, this proposal will allow them to continue analysis on the Milagro data.
IceCube and Milagro are strongly connected with other experiments in the field of Particle Astrophysics as they are part of a multi-messenger survey of the high energy sky. These experiments have a strong appeal both to the physics students and the general public and this group has an established track record in both public outreach and providing strong scientific and educational opportunities for undergraduate and graduate students and post-doctoral fellows.
. The research in particle astrophysics was focused in the area of using high-energy gamma-rays and neutrinos to search for astrophysical objects to elucidate the astrophysical mechanisms at work in the universes most energetic objects, and to shed light on the nature and source of the highest energy cosmic rays that continually bombard the earth. These are referred to as gamma-ray astronomy and neutrino astronomy. The research in neutrino astronomy was performed using a new instrument called IceCube being constructed at the Antarctic south pole station. The instrument completed in December of 2010 instruments approximately one cubic-kilometer of ice deep under the geographic south pole. The instrument was operated to detect high-energy neutrinos and essentially develop a map of the neutrino sky. Using this map, scientists on this grant searched for astrophysical point sources to develop an understanding of what the high energy looks like. The energies observed using neutrinos was on the order of one trillion times the typical energy of optical astronomy. A number of significant scientific results were published in the scientific journals, and results were presented at international scientific conferences. The research in high-energy gamma-ray astronomy made astronomical sky-maps using high energy gamma-rays, which were about one trillion higher in energy then typical optical astronomy. A number of galactic and extragalactic sources have been identified and studied using this new type of telescope called Milagro. Based on the success of the results from Milagro planning and research and development began on a new generation of instrument with higher sensitivity. This new instrument is now being constructed in the mountains of Mexico.