118364186
Measurement of Spin Effects in pp Elastic Scattering Using the Polarized Beam at the AGS
Using the recently developed 18.5 GeV/c AGS polarized proton beam and a polarized proton target we measured the analyzing power, A, and the spin-spin correlation parameter, Ann, in medium-P2 ⊥ proton-proton elastic scattering. We found sharp dips in both A and Ann, which occur at different P2 ⊥ values. The unexpected sharp structure in the spin-spin force occurs near P2 ⊥ = 2.3 [GeV/c]2 where the elastic cross-section has no apparent structure.
121463461
Overcoming depolarizing resonances with a Siberian snake
28227992
First test of the Siberian snake magnet arrangement to overcome depolarizing resonances in a circular accelerator.
We studied the G\ensuremath{\gamma}=2 imperfection depolarizing resonance at 108 MeV, both with and without a Siberian snake, by varying the resonance strength while storing beams of 104- and 120-MeV polarized protons at the Indiana University Cooler Ring. We used a cylindrically symmetric polarimeter to simultaneously study the effect of a depolarizing resonance on both the vertical and radial components of the polarization. AT 104 MeV we found that the Siberian snake eliminated the effect of the nearby G\ensuremath{\gamma}=2 depolarizing resonance.
26176644
Overcoming intrinsic and synchrotron depolarizing resonances with a Siberian snake.
We overcame the strong {ital G}{gamma}={minus}3+{nu}{sub {ital y}} intrinsic depolarizing resonance using a Siberian snake acting on a stored beam of 177-MeV polarized protons at the Indiana University Cooler Ring. We also saw the first evidence for a synchrotron depolarizing resonance in a proton ring. Two synchrotron resonances were studied by varying the rf accelerating voltage and the imperfection field at 104 MeV. The Siberian snake also overcame these synchrotron depolarizing resonances.
137334067
First scientific application of the membrane cryostat technology
We report on the design, fabrication, performance and commissioning of the first membrane cryostat to be used for scientific application. The Long Baseline Neutrino Experiment (LBNE) has designed and fabricated a membrane cryostat prototype in collaboration with IHI Corporation (IHI). Original goals of the prototype are: to demonstrate the membrane cryostat technology in terms of thermal performance, feasibility for liquid argon, and leak tightness; to demonstrate that we can remove all the impurities from the vessel and achieve the purity requirements in a membrane cryostat without evacuation and using only a controlled gaseous argon purge; to demonstrate that we can achieve and maintain the purity requirements of the liquid argon during filling, purification, and maintenance mode using mole sieve and copper filters from the Liquid Argon Purity Demonstrator (LAPD) R&D project. The purity requirements of a large liquid argon detector such as LBNE are contaminants below 200 parts per trillion oxygen equiva...
55616452
Microwave driven extraction of stabilized spin polarized atomic hydrogen
Abstract The storage of ultracold spin-polarized hydrogen atoms offers the possibility of producing a high intensity nuclear polarized atomic hydrogen jet. We stored electron spin polarized atomic hydrogen at 0.4 K in an open 5 T magnetic storage cell. We also observed directly, for the first time, the extraction of hydrogen atoms from the storage cell by flipping their spins using a microwave driven transition. The results are being used to design a high intensity jet of nuclear polarized atomic hydrogen to be used as an internal target in the 400 GeV to 3 TeV UNK accelerator.
115174174
The characteristic initial value problem for plane symmetric spacetimes with weak regularity
We investigate the existence and the global causal structure of plane symmetric spacetimes with weak regularity when the matter consists of an irrotational perfect fluid with pressure equal to its mass-energy density. Our theory encompasses the class of W1, 2 regular spacetimes whose metric coefficients have square-integrable first-order derivatives and whose curvature must be understood in the sense of distributions. We formulate the characteristic initial value problem with data posed on two null hypersurfaces intersecting along a two-plane. Relying on Newman–Penrose's formalism and expressing our weak regularity conditions in terms of the Newman–Penrose scalars, we arrive at a fully geometrical formulation in which, along each initial hypersurface, two scalar fields describing the incoming radiation must be prescribed in L1 and W−1, 2, respectively. To analyze the future boundary of such a spacetime and identify its global causal structure, we introduce a gauge that reduces the Einstein equations to a coupled system of wave equations and ordinary differential equations for well-chosen unknowns. We prove that, within the weak regularity class under consideration and for generic initial data, a true spacetime singularity forms in finite proper time. Our formulation is robust enough so that propagating discontinuities in the curvature or in the matter variables do not prevent us from constructing a spacetime whose curvature generically blows up on the future boundary. Earlier work on the problem studied here was restricted to sufficiently regular and vacuum spacetimes.
119467937
The spherically symmetric collapse of a massless scalar field
We report on a numerical study of the spherically symmetric collapse of a self-gravitating massless scalar field. Earlier results of Choptuik (1992, 1994) are confirmed. The field either disperses to infinity or collapses to a black hole, depending on the strength of the initial data. For evolutions where the strength is close to but below the strength required to form a black hole, we argue that there will be a region close to the axis where the scalar curvature and field energy density can reach arbitrarily large levels, and which is visible to distant observers.
121061690
Can spin avert singularities
TRAUTMAN has suggested1 that the introduction of intrinsic spin effects into general relativity through the Einstein-Cartan torsion theory may avert a gravitational singularity. In this note we suggest that the singularity is avoided only because of the high symmetry of the model used.
122681442
The scalar wave equation in a Schwarzschild space-time
This paper studies the asymptotic behaviour of solutions of the zero rest mass scalar wave equation in the Schwarzschild space-time in a neighbourhood of spatial infinity which includes parts of future and past null infinity. The behaviour of such fields is essentially different from that which occurs in a flat space-time. In particular fields which have a Bondi-type expansion in powers of 'r-1’ near past null infinity do not have such an expansion near future null infinity. Further solutions which have physically reasonable Cauchy data probably fail to have Bondi-type expansions near null infinity.
120706551
Advanced General Relativity
1. Differential geometry 2. Spinors 3. Asymptopia 4. The characteristic initial value problem.