96922270
Application of accelerator mass spectrometry in aluminum metabolism studies
Abstract The recent recognition that aluminum causes toxicity in uremie patients and may be associated with Alzheimer's disease has stimulated many studies of its biochemical effects. However, such studies were hampered by the lack of a suitable tracer. In a novel experiment, we have applied the new technique of accelerator mass spectrometry to investigate aluminum kinetics in rats, using as a marker the long-lived isotope 26 Al. We present the first aluminum kinetic model for a biological system. The results clearly demonstrate the advantage this technique holds for isotope tracer studies in animals as well as in humans.
38997255
Prototype detector for ultrahigh energy neutrino detection
Abstract Necessary technical experience is being gained from successful construction and deployment of current prototype detectors to search for UHE neutrinos in Antarctica, Lake Baikal in Russia, and the Mediterranean. The prototype detectors have also the important central purpose of determining whether or not UHE neutrinos do in fact exist in nature by observation of at least a few UHE neutrino-induced leptons with properties that are not consistent with expected backgrounds. We discuss here the criteria for a prototype detector to accomplish that purpose in a convincing way even if the UHE neutrino flux is substantially lower than predicted at present.
53975074
Future 'realtime' solar neutrino experiments
I summarize here the goals of the future solar neutrino program, and the proposed experiments.
39057593
Solving the solar neutrino problem.
Building a detector the size of a 10-story building two kilometers underground is a strange way to study solar phenomena. Yet that has turned out to be the key to unlocking a decades-old puzzle about the physical processes occurring inside the sun. English physicist Arthur Eddington suggested as early as 1920 that nuclear fusion powered the sun, but efforts to confirm critical details of this idea in the 1960s ran into a stumbling block: experiments designed to detect a distinctive by-product of solar nuclear fusion reactions—ghostly particles called neutrinos—observed only a fraction of the expected number of them. It was not until 2002, with the results from the underground
119647577
Reply to comment on ‘Using cold atoms to measure neutrino mass’
We discuss questions raised concerning the proposal of kinematically reconstructing the neutrino mass using an ultracold source of tritium atoms (Otten E W 2011 New J. Phys. 13 078001). We provide further details about our two-dimensional fit and emphasize the importance of simultaneously utilizing information from both the neutrino mass squared peak and the β-spectrum. We also explain how the simulation evolved over various drafts of the paper, and we comment on future directions for additional simulation work, including more detailed simulations of spectrometers and electromagnetic field variations.
18217236
The calibration of the Sudbury Neutrino Observatory using uniformly distributed radioactive sources
The production and analysis of distributed sources of 24Na and 222Rn in the Sudbury Neutrino Observatory (SNO) are described. These unique sources provided accurate calibrations of the response to neutrons, produced through photodisintegration of the deuterons in the heavy water target, and to low energy betas and gammas. The application of these sources in determining the neutron detection efficiency and response of the 3He proportional counter array, and the characteristics of background Cherenkov light from trace amounts of natural radioactivity is described.
10591697
SANEPIC: a mapmaking method for time stream data from large arrays
We describe a mapmaking method that we have developed for the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) experiment, but which should have general application to data from other submillimeter arrays. Our method uses a maximum likelihood-based approach, with several approximations, which allows images to be constructed using large amounts of data with fairly modest computer memory and processing requirements. This new approach, Signal and Noise Estimation Procedure Including Correlations (SANEPIC), builds on several previous methods but focuses specifically on the regime where there are a large number of detectors sampling the same map of the sky, and explicitly allowing for the possibility of strong correlations between the detector time streams. We provide real and simulated examples of how well this method performs compared with more simplistic mapmakers based on filtering. We discuss two separate implementations of SANEPIC: a brute-force approach, in which the inverse pixel-pixel covariance matrix is computed, and an iterative approach, which is much more efficient for large maps. SANEPIC has been successfully used to produce maps using data from the 2005 BLAST flight.
2907589
The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) 2005: Calibration and Targeted Sources
The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) operated successfully during a 100 hr flight from northern Sweden in 2005 June (BLAST05). As part of the calibration and pointing procedures, several compact sources were mapped, including solar system, Galactic, and extragalactic targets, specifically Pallas, CRL 2688, LDN 1014, IRAS 20126+4104, IRAS 21078+5211, IRAS 21307+5049, IRAS 22134+5834, IRAS 23011+6126, K3-50, W75N, and Mrk 231. One additional source, Arp 220, was observed and used as our primary calibrator. Details of the overall BLAST05 calibration procedure are discussed here. The BLAST observations of each compact source are described, flux densities and spectral energy distributions are reported, and these are compared with previous measurements at other wavelengths. The 250, 350, and 500 μm BLAST data can provide useful constraints to the amplitude and slope of the submillimeter continuum, which in turn may be useful for the improved calibration of other submillimeter instruments.
119310570
Attitude determination for balloon-borne experiments
An attitude determination system for balloon-borne experiments is presented. The system provides pointing information in azimuth and elevation for instruments flying on stratospheric balloons over Antarctica. In-flight attitude is given by the real-time combination of readings from star cameras, a magnetometer, sun sensors, GPS, gyroscopes, tilt sensors and an elevation encoder. Post-flight attitude reconstruction is determined from star camera solutions, interpolated by the gyroscopes using an extended Kalman Filter. The multi-sensor system was employed by the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol), an experiment that measures polarized thermal emission from interstellar dust clouds. A similar system was designed for the upcoming flight of Spider, a Cosmic Microwave Background polarization experiment. The pointing requirements for these experiments are discussed, as well as the challenges in designing attitude reconstruction systems for high altitude balloon flights. In the 2010 and 2012 BLASTPol flights from McMurdo Station, Antarctica, the system demonstrated an accuracy of < 5’ rms in-flight, and < 5” rms post-flight.
120848727
Final state branching ratio in the Be 7 decay
The fractional decay branch in the EC decay of $^{7}\mathrm{Be}$ leading to the first excited state of $^{7}\mathrm{Li}$ has been measured. $^{7}\mathrm{Be}$ ions from a beam produced by a tandem Van de Graaff accelerator were implanted into a surface-barrier detector; the decay $\ensuremath{\gamma}$ rays were then counted using a well-shielded Ge(Li) detector of known absolute efficiency. The resulting decay branch, (10.10\ifmmode\pm\else\textpm\fi{}0.45)%, is in good agreement with previously published values and in strong disagreement with a recent measurement.
117879343
Planning the Future of U.S. Particle Physics (Snowmass 2013): Chapter 7: Underground Laboratory Capabilities
These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 7, on Underground Laboratory Capabilities, discusses the prospects and requirements for large underground experiments such as those for neutrino physics, proton decay, and dark matter.