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Ultra-relativistic heavy ions and the CBA

Description: The study of ultra-relativistic heavy ions at an accelerator such as the CBA provides a unique glimpse of matter as it may have appeared in the early universe. This hot dense matter very probably appears as a quark-gluon plasma which expands and cools into hadronic matter. The CBA would provide data at the very highest energies, and produce matter at the highest energy densities. The possibility of using a cyclotron to inject very heavy ions into the AGS and then into the CBA would also allow the production of quark-gluon matter at higher energy densities than would light ions, and would make the matter in a larger volume where surface effects are minimized. At the highest energies with very heavy ions, there is great flexibility in the experimental signals which might be studied, as well as the nature of the matter which is produced. Some of the possibilities are discussed. (WHK)
Date: January 1, 1982
Creator: McLerran, L.D.
Partner: UNT Libraries Government Documents Department

1/2/sup +/. -->. 1/2/sup -/ beta decay of /sup 19/Ne and the parity nonconserving NN force

Description: A branching ratio of (1.20 +- 0.20) x 10/sup -4/ is obtained for the ..beta../sup +/ decay of /sup 19/Ne to the 110 keV 1/2/sup -/ level of /sup 19/F. This transition (presumably dominated by the ..delta..J/sup ..pi../ = 0/sup -/ axial charge operator) provides a crucial test of wavefunctions used in interpreting the parity mixing of the ground and 110 keV levels of /sup 19/F. These wavefunctions, which yield a parity mixing larger than that observed experimentally, also predict too large a ..beta../sup +/ decay rate.
Date: January 1, 1978
Creator: Adelberger, E.G.; Hindi, M.M.; Hoyle, C.D.; Swanson, H.E. & Von Lintig, R.D.
Partner: UNT Libraries Government Documents Department

Astrophysical cosmology

Description: The last several years have seen a tremendous ferment of activity in astrophysical cosmology. Much of the theoretical impetus has come from particle physics theories of the early universe and candidates for dark matter, but what promise to be even more significant are improved direct observations of high z galaxies and intergalactic matter, deeper and more comprehensive redshift surveys, and the increasing power of computer simulations of the dynamical evolution of large scale structure. Upper limits on the anisotropy of the microwave background radiation are gradually getting tighter and constraining more severely theoretical scenarios for the evolution of the universe. 47 refs.
Date: January 1, 1986
Creator: Bardeen, J.M.
Partner: UNT Libraries Government Documents Department

Polarized proton radiative capture studies of giant resonances

Description: Several interesting E1, M1, and E2 resonance studies in (p Vector,..gamma..) reactions are discussed. These include a unique determination of E1 amplitudes in the /sup 12/C(p Vector,..gamma../sub 0/)/sup 13/N reaction, E2 strength in the /sup 15/N(p Vector,..gamma../sub 0/)/sup 16/O reaction, M1 decays to the ground states and to the excited O/sup +/ states of the doubly magic /sup 16/O and /sup 40/Ca nuclei, and the M1 ..gamma..-decay of the stretched 4/sup -/, T = 1 particle-hole state in /sup 16/O. 8 figures.
Date: January 1, 1980
Creator: Snover, K.A.
Partner: UNT Libraries Government Documents Department

Perturbative QCD: an overview

Description: Recent progress in the utilization of perturbative quantum chromodynamics to study lepton-hadron and hadron-hadron reactions is reviewed. Interest is focused on the connections between the various results and the implications for the parton model as a phenomenological tool and as a vehicle to test quantum chromodynamics. 42 references.
Date: January 1, 1979
Creator: Ellis, S.D.
Partner: UNT Libraries Government Documents Department

Radiative capture studies of the electromagnetic decays of highly excited states

Description: Selected examples of interesting E1, M1, and E2 resonance studies in (p,..gamma..) and (..cap alpha..,..gamma..) reactions are discussed. These include a unique determination of E1 amplitudes in the /sup 12/C(P,..gamma../sub 0/)/sup 13/N reaction, E2 strength in light nuclei, M1 decays to the ground states and to the excited O/sup +/ states of the doubly magic /sup 16/O and /sup 40/Ca nuclei, second harmonic E1 resonances in (p,..gamma..), and M1 ..gamma..-decay of stretched particle-hole states in /sup 16/O and /sup 28/Si.
Date: January 1, 1980
Creator: Snover, K.A.
Partner: UNT Libraries Government Documents Department

Testing quantum chromodynamics in electron-positron annihilation at high energies. [Review]

Description: Various measures of the distribution of hadronic energy produced in high energy electron-positron annihilation provide precise tests of the promising fundamental theory of hadronic physics, quantum chromodynamics. Recent work at the University of Washington on such energy cross sections is reviewed.
Date: January 1, 1979
Creator: Brown, L.S.
Partner: UNT Libraries Government Documents Department

Charge symmetry breaking in the neutron proton system

Description: Two consequences of charge symmetry breaking (CSB) in the n-p system are examined. In n-p elastic scattering, CSB nuclear forces cause a difference between the polarizations of the neutron and the proton scattered in opposite directions in the center of mass system. The expected differences in polarizations due to one boson exchanges, particularly a photon exchange, isospin mixed mesons, and a pion (with the n-p mass difference taken into account), are computed. The calculated polarization difference is typically of the order of several tenths of a percent. In np ..-->.. d..pi../sup 0/, the CSB of nuclear forces can be tested by measuring the asymmetry of the angular distribution of deuterons about 90/sup 0/ in the center of mass frame. The expected asymmetry is calculated for one boson exchange CSB mechanisms, as in the elastic scattering. The asymmetry caused by the mixed n-..pi../sup 0/ exchange is dominant, but all of the mechanisms contribute asymmetries with similar angular dependences. The maximum assymmetry is about 0.8% at /sup 0/; the average is about 0.2%.
Date: December 1, 1979
Creator: Cheung, C.Y.; Henley, E.M. & Miller, G.A.
Partner: UNT Libraries Government Documents Department

Dryson equations, Ward identities, and the infrared behavior of Yang-Mills theories. [Schwinger-Dyson equations, Slavnov-Taylor identities]

Description: It was shown using the Schwinger-Dyson equations and the Slavnov-Taylor identities of Yang-Mills theory that no inconsistency arises if the gluon propagator behaves like (1/p/sup 2/)/sup 2/ for small p/sup 2/. To see whether the theory actually contains such singular long range behavior, a nonperturbative closed set of equations was formulated by neglecting the transverse parts of GAMMA and GAMMA/sub 4/ in the Schwinger-Dyson equations. This simplification preserves all the symmetries of the theory and allows the possibility for a singular low-momentum behavior of the gluon propagator. The justification for neglecting GAMMA/sup (T)/ and GAMMA/sub 4//sup (T)/ is not evident but it is expected that the present study of the resulting equations will elucidate this simplification, which leads to a closed set of equations.
Date: January 1, 1979
Creator: Baker, M.
Partner: UNT Libraries Government Documents Department

Ultra-relativistic heavy ions and cosmic rays

Description: The collisions of ultra-relativistic heavy ions, E/sub /N/ greater than or equal to 1 TeV/nucleon are most interesting, since, at these energies, matter is produced at sufficiently high energy density that a quark-gluon plasma has a good chance to form. Very heavy ions are also most interesting since the matter forms in a larger volume than for light ions, and the matter is at a somewhat higher energy density. At very high energies with very heavy ions there is great flexibility in the experimental signals which might be studied, as well as the nature of the matter which is produced. The fragmentation region and central region provide different environments where a plasma might form. The former is baryon rich while the central region is high temperature with low baryon number density and is not accessible except at very high energies.
Date: May 1, 1983
Creator: McLerran, L.
Partner: UNT Libraries Government Documents Department

Theory of atomic parity violating experiments. [Review]

Description: A review of atomic calculations relevant to the Bi parity nonconservation experiments is presented. The following were included to date: relativistic Hartree-Fock, intermediate coupling, configuration mixing and RPA-type shielding. There is disagreement between two shielding calculations. Using mean values of these shielding corrections, one obtains for the mixing ratios R = -10.5 (876 nm) and -14(648 nm); based on uncertainty in the shielding and neglected diagrams, the theoretical uncertainty was estimated to be less than 50%. There is a disagreement of five and three standard deviations with the UW and Oxford experiments respectively, but agreement with the Novosibirsk experiment. 16 references.
Date: January 1, 1978
Creator: Wilets, L.
Partner: UNT Libraries Government Documents Department

Summary of Kaon Factory Workshop. [8th Inter. Conf. High-Energy Phys. Nuclear Structure, Canada, 1979]

Description: Some highlights of the physics sessions of the Kaon Factory Workshop held in connection with the 8th International Conference on High-Energy Physics and Nuclear Structure in British Columbia in 1979 are presented. Particular emphasis is placed on the different investigations that can be carried out with kaons and antiprotons as opposed to pions and protons. Some data on K + /sup 12/C elastic scattering are shown. 3 figures.
Date: August 1, 1979
Creator: Henley, E.M.
Partner: UNT Libraries Government Documents Department

Some symmetries in nuclei

Description: Internal and space-time symmetries are discussed in this group of lectures. The first of the lectures deals with an internal symmetry, or rather two related symmetries called charge independence and charge symmetry. The next two discuss space-time symmetries which also hold approximately, but are broken only by the weak forces; that is, these symmetries hold for both the hadronic and electromagnetic forces. (GHT)
Date: September 1, 1981
Creator: Henley, E.M.
Partner: UNT Libraries Government Documents Department

Jet acollinearity and quark form factors

Description: Perturbative Quantum Chromodynamic corrections involving the emission of gluons which are both soft and collinear are discussed for both hadronic production of lepton pairs and e/sup +/e/sup -/ annihilation. The result is an exponential, double logarithmic quark form factor. The effect of sub-leading corrections and the possible experimental observation of the form factor are discussed.
Date: January 1, 1980
Creator: Stirling, W. J.
Partner: UNT Libraries Government Documents Department

Giant resonance effects in radiative capture

Description: The technique of capture reaction studies of giant resonance properties is described, and a number of examples are given. Most of the recent work of interest has been in proton capture, in part because of the great utility (and availability) of polarized beams; most of the discussion concerns this reaction. Alpha capture, which has been a useful tool for exploring isoscalar E2 strength, and neutron capture are, however, also treated. 46 references, 14 figures. (RWR)
Date: January 1, 1979
Creator: Snover, K. A.
Partner: UNT Libraries Government Documents Department

High pressure x-ray absorption studies of phase transitions

Description: High pressure generally changes all of the properties of substances, leading to phase transitions in many cases. This paper reviews how such phase changes reveal themselves in x-ray absorption spectra. Examples are given using the salts NaBr, RbCl, CuBr, and SnSe. (DLC)
Date: January 1, 1984
Creator: Tranquada, J.M.; Ingalls, R. & Crozier, E.D.
Partner: UNT Libraries Government Documents Department

Achieving cold antiprotons in a Penning trap

Description: The current state of proton/electron trapping sensitivity at Washington requires only small numbers (less than or equal to 100) of anti p be trapped in order to achieve high signal to noise ratios. We therefore investigated a anti p trapping scheme based on stopping foils which, in the simplest case, require no auxiliary decelerator/cooler past a LEAR (or equivalent) stage. Cooling of the trapped particles could be accomplished via the damping provided by an external resistor as in all of the other experiments. The rate of this cooling would be rather low, even in the most ideal case, and likely would be much lower when the electrostatic anharmonicity of such a trap is realistically considered. We thereby examined a possible alternate cooling scheme, electron cooling with a buffer gas of cold electrons, in order to improve the cooling rate. 18 references.
Date: August 1, 1984
Creator: Kells, W.; Gabrielse, G. & Helmerson, K.
Partner: UNT Libraries Government Documents Department

Spin--wave spectrum of an amorphous ferromagnet

Description: The spin-wave spectruin of an amorphous Heisenberg ferromagnet is calculated by a diagrammatic expansion making use of a transformation due to Taylor and Wu Phys. Rev., B2: 1752 (1970). The upper limit of the spectrum is found to occur at frequencies below that of the corresponding crystalline system, while the low-frequency part of the spectrum is enhanced. Internal van Hove singularities are absent in the spin-wave spectrum of the amorphous ferromagnet. (auth)
Date: January 1, 1973
Creator: Gubernatis, J.E. & Taylor, P.L.
Partner: UNT Libraries Government Documents Department

Ion chambers for fluorescence and laboratory EXAFS detection

Description: It is possible to design gas ionization chambers with a noise equivalence of 10/sup 3/ photons per second for 10 keV x-radiation. With such a low noise level, ion detectors can be used for laboratory EXAFS facilities and fluorescence detectors at national synchrotron facilities where the detected signal is above 10/sup 3/ photons/s. In such use the ion chambers are limited by statistical noise and produce as good a signal to noise as counting detectors. The advantages of ion chambers are simplicity, high linearity at high counting rates, and large detecting area.
Date: January 1, 1981
Creator: Stern, E.A.; Elam, W.T.; Bunker, B.A.; Lu, K. & Heald, S.M.
Partner: UNT Libraries Government Documents Department

Ex-vessel water-level and fission-product monitoring for LWR

Description: Given that the need for direct measurement of reactor coolant inventory under operational or abnormal conditions remains unsatisfied, a high-energy gamma-ray detection system is described for ex-vessel monitoring. The system has been modeled to predict response in a PWR, and the model has been validated with a LOFT LOCA sequence. The apparatus, situated outside the pressure vessel, would give relative water level and density over the entire vessel height and distinguish differing levels in the downcomer and core. It would also have significant sensitivity after power shutdown because of high-energy gamma rays from photoneutron capture, the photoneutrons being the result of fission-product decay in the core. Fission-products released to the coolant and accumulated in the top of a PWR vessel would also be theoretically detectable.
Date: January 1, 1988
Creator: DeVolpi, A. & Markoff, D.
Partner: UNT Libraries Government Documents Department

Status and first results of BNL experiment 777: A search for K/sup +/. -->. pi. /sup +/. mu. /sup +/e/sup -/ and a study of K/sup +/. -->. mu. /sup +/e/sup +/e/sup -/

Description: Results of our search for short lived neutral particles emitted in K/sup +/ decay are given. We also seek to make an accurate measurement of the branching ratio for ..pi../sup 0/ ..-->.. e/sup +/e/sup -/ by looking for the decay chain K/sup +/ ..-->.. ..pi../sup +/..pi../sup 0/, ..pi../sup 0/ ..-->.. e/sup +/e/sup -/. The world average branching ratio for this decay is (1.8 +- 0.7) x 10/sup -7/ based on about 30 events from two experiments. Theory predicts that this branching ratio should be of order 6 x 10/sup -8/. If the branching ratio remains at the 2 x 10/sup -7/ level when measured with smaller errors, this could be an indication of new physics. 24 refs., 7 figs.
Date: October 1, 1987
Creator: Baker, N.J.; Gordon, H.A.; Lazarus, D.M.; Polychronakos, V.A.; Rehak, P.; Tannenbaum, M.J. et al.
Partner: UNT Libraries Government Documents Department

Effects of local mass anomalies in Eoetvoes-like experiments

Description: We consider in detail the effects of local mass anomalies in Eoetvoes-like experiments. It is shown that in the presence of an intermediate-range non-gravitational force, the dominant contributions to both the sign and magnitude of the Eoetvoes anomaly may come from nearby masses and not from the earth as a whole. This observation has important implications in the design and interpretation of future experiments, and in the formulation of unified theories incorporating new intermediate-range forces.
Date: May 26, 1986
Creator: Talmadge, C.; Aronson, S.H. & Fischbach, E.
Partner: UNT Libraries Government Documents Department