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Simulation of turbulence in fireballs

Description: The ALE technique is applied to the calculation of a small yield, low altitude nuclear explosion. When artificial diffusion effects caused by numerical errors are minimized, the fireball rises too rapidly, reaching an altitude in excess of that which is observed. This suggests that turbulent diffusion and entrainmert may be important. Hence, a turbulence model has been added to later calculations of the fireball dynamics. Some of the more important features of the calculational technique and the turbulence model are discussed. Preliminary results for a set of turbulence parameters and a particular low altitude fireball are presented. (auth)
Date: November 1, 1973
Creator: Ruppel, H.M.; Gentry, R.A. & Daly, B.J.
Partner: UNT Libraries Government Documents Department

Search for high-energy muon neutrinos from the"naked-eye" GRB080319B with the IceCube neutrino telescope

Description: We report on a search with the IceCube detector for high-energy muon neutrinos from GRB080319B, one of the brightest gamma-ray bursts (GRBs) ever observed. The fireball model predicts that a mean of 0.12 events should be detected by IceCube for a bulk Lorentz boost of the jet of 300. In both the direct on-time window of 66 s and an extended window of about 300 s around the GRB, there was no excess found above the background. The 90% C.L. upper limit on the number of track-like events from the GRB is 2.7, corresponding to a muon neutrino fluence limit of 9.0 x 10{sup -3} erg cm{sup -2} in the energy range between 145 TeV and 2.1 PeV, which contains 90% of the expected events.
Date: February 1, 2009
Creator: Collaboration, IceCube & Abbasi, R.
Partner: UNT Libraries Government Documents Department

High Energy Gamma-Ray Emission from Gamma-Ray Bursts - Before GLAST

Description: Gamma-ray bursts (GRBs) are short and intense emission of soft {gamma}-rays, which have fascinated astronomers and astrophysicists since their unexpected discovery in 1960s. The X-ray/optical/radio afterglow observations confirm the cosmological origin of GRBs, support the fireball model, and imply a long-activity of the central engine. The high-energy {gamma}-ray emission (> 20 MeV) from GRBs is particularly important because they shed some lights on the radiation mechanisms and can help us to constrain the physical processes giving rise to the early afterglows. In this work, we review observational and theoretical studies of the high-energy emission from GRBs. Special attention is given to the expected high-energy emission signatures accompanying the canonical early-time X-ray afterglow that was observed by the Swift X-ray Telescope. We also discuss the detection prospect of the upcoming GLAST satellite and the current ground-based Cerenkov detectors.
Date: November 29, 2011
Creator: Fan, Yi-Zhong & Piran, Tsvi
Partner: UNT Libraries Government Documents Department

On the afterglow and host galaxy of GRB 021004: A comprehensivestudy with the Hubble Space Telescope1

Description: We report on Hubble Space Telescope (HST) observations of the late-time afterglow and host galaxy of GRB 021004 (z = 2.33).Although this gamma-ray burst (GRB) is one of the best observed so far in terms of sampling in the time domain, multi-wavelength coverage and polarimetric observations, there is large disagreement between different measurements and interpretations of this burst in the literature. We have observed the field of GRB 021004 with the HST at multiple epochs from 3 days until almost 10 months after the burst. With STI S prism and G430L spectroscopy we cover the spectral region from about 2000 Angstrom to 5700 Angstrom corresponding to 600 1700 Angstrom in the rest frame. From the limit on the flux recovery bluewards of the Lyman-limit we constrain the H I column density to be above 1 x 1018 cm-2 (5 sigma). Based on ACS and N ICMOS imaging we find that the afterglow evolved a chromatically within the errors (any variation must be less then 5 percent) during the period of HST observations. The color changes observed by other authors during the first four days must be related to a 'noisy' phenomenon superimposed on an afterglow component with a constant spectral shape. This also means that the cooling break has remained on the blue side of the optical part of the spectrum for at least two weeks after the explosion. The optical to X-ray slope OX is consistent with being the same at 1.4 and 52.4 days after the burst. This indicates that the cooling frequency is constant and hence, according to fireball models, that the circumburst medium has a constant density profile. The late-time slope of the light curve (alpha 2, F nu proportional to t-alpha2) is in the range 2 = 1.8-1.9, although inconsistent with a single power-law. This ...
Date: December 1, 2004
Creator: Fynbo, J.P.U.; Gorosabel, J.; Smette, A.; Fruchter, A.; Hjorth,J.; Pedersen, K. et al.
Partner: UNT Libraries Government Documents Department

A Proposal of the Photoemulsion Experiment at the National Accelerator Laboratory (Batavia)

Description: The experiments using a cloud chamber in a magnetic field and an ionizing calorimeter exposed io cosmic rays have been performed at the Lebedev Physical Institute I 1-3 I. They have shown that the hadron interactions with a LiH target at the energies of 200-700 Gev can be explained on the basis of the fireball model, supposing one fireball formation in a peripherical process, for about 50 per cent of events. The experiments carried out at the accelerator beams using the photoemulsion method at CERN (Eo = 2l-24 Gev) I 4 I and at Serpukhov (Eo = 60 Gev) I 5 I have indicated that the same model can describe the essential part of the pN- and {pi}iN - interactions (the quasi-free nucleon interactions are selected with the help of the criteria, approbated at the energies of {approx}20 Gev). It seems to be very important to continue this photoemulsion experiment at the energies of 200-500 Gev at the Batavia accelerator retaining the previous method of selecting the quasi-free nucleon interactions and measuring besides the emission angles of the charged particles also the momenta of these particles by their Coulomb scattering. Under the favourable conditions of exposure of the Soviet emulsions one can expect the value of the measurement precision of the particles moments to be {approx} 30% at the particle momenta values p {approx} 30-50 Gev/c. This expected precision, at least, will not be worse than that obtained in the last experiments I 1-3 I, having an advantage of a much better angular resolution, an unambiguous determination of the nature and energy of the primary particles and better statistics. So we hope to realize a new more reliable check of the fireball model application and also any other model concerning the multiple production of particles. The second scientific problem consists ...
Date: May 30, 1972
Creator: Dobrotin, N.A.; Zhdanov, G.B. & Tretyakova, M.I.
Partner: UNT Libraries Government Documents Department

Freeze-out conditions in ultrarelativistic heavy-ion collisions

Description: The authors present recent results on single particle transverse momentum distributions of pions, kaons, and protons, measured in CERN Experiment NA44, of 200A{center_dot}FeV/c S+S and 158A{center_dot}GeV/c Pb+Pb central collisions. By comparing these data with thermal and transport models, freeze-out parameters like the temperature T{sub fo} and the chemical potentials ({mu}{sub q}, {mu}{sub s}) are extracted and discussed.
Date: July 1, 1996
Creator: Xu, N. & Collaboration, NA44
Partner: UNT Libraries Government Documents Department

Search for collective phenomena in relativistic nuclear collisions

Description: After some general introductory material, the weakness of the fireball/fire streak model is illustrated, and it is indicated that more complex models are both necessary and available. The single-particle spectra of nucleons, clusters, and pions are discussed, and then attention is focused on the fate of the target nucleus and possible evidence of collective phenomena. Finally, data on central collisions that reflect the nature of the energy flux in the target nucleus are discussed. 26 figures. (RWR)
Date: June 1, 1980
Creator: Gutbrod, H.H.
Partner: UNT Libraries Government Documents Department

Very high energy nuclear collisions: the asymptotic hadron spectrum, anti-nuclei, hyper-nuclei, and quark phase

Description: The possibilities of hadron production are considered. Included are hadrons never to be discovered, relevance of the study, means of production, thermodynamics of hadronic matter, three examples of hadronic spectra, the temperature, composition of the initial fireball, expansion of the fireball, pre-freeze-out radiation, antinuclei, hypernuclei, and the quark phase. 17 references. (JFP)
Date: January 2, 1978
Creator: Glendenning, N.K.
Partner: UNT Libraries Government Documents Department

Pseudorapidity distributions, nuclear stopping, and the failures and successes of the fireball model

Description: Pseudorapidity distributions of multiplicity and transverse energy are a useful probe of nuclear stopping. Emulsion results at the AGS and CERN, as well as E/sub T/ measurements at both laboratories are discussed, and show that the fireball model with crisp and precise predictions of the pseudorapidity distributions, utterly fails to reproduce the measurements. By stark contrast, the fireball model is very successful in predicting the observed ratio of E/sub T/ production in central /sup 32/S and /sup 16/O interactions in Au and other heavy targets. This conundrum is explored and explained, leading to a systematic comparison of measurements from all the RHI experiments at the AGS and CERN. 14 refs., 3 figs.
Date: May 1, 1989
Creator: Tannenbaum, M.J.
Partner: UNT Libraries Government Documents Department

Aspects of data on the breakup of highly excited nuclei

Description: There is an awakening of theoretical interest in the mechanisms by which nuclear fragments (4 less than or equal to A less than or equal to 150) are produced in violent collisions of heavy ions. With this in mind we review some aspects of the available experimental data and point out some challenging features against which to test the models. The concept of evaporation is tremendously powerful when applied to pieces of nuclei of low excitation (1 or 2 MeV/u). Current interest focuses on higher excitations, at the point where the binding energy of the system vanishes. This is the transition from liquid nuclei to a gas of nucleons, and it may be that the critical phenomena that certainly exist in infinite nuclear matter will be manifest in finite nuclei under these conditions.
Date: May 1, 1983
Creator: Warwick, A.I.; Wieman, H.H.; Gutbrod, H.H.; Ritter, H.G.; Stelzer, H.; Weik, F. et al.
Partner: UNT Libraries Government Documents Department

Perspective on relativistic nuclear collisions

Description: The importance of experiments detecting more than one particle is pointed out. The production of nuclei far from stability in peripheral collisions and the expectations for the explosive disassembly of dense nuclear matter (nuclear fireball) and some evidence for it are related. Pion interferometry concerns the measurement of correlations in the momentum and energy of two identical pions; the subject is discussed in relation to incoherent production, coherent production, partially coherent production, final-state interactions, impact parameter average, and outlook. Much of the paper deals with an assessment of the possibility of determining the form of the hadronic spectrum in the high-mass region through nuclear collisions at ultrarelativistic energies. The subject is developed under the following topics: perspective, the initial fireball, isoergic equilibrium expansion of the fireball, quasi-dynamical expansion, quark matter, and the mass degree of freedom. The quasi-dynamical model obtained indicates that certain parameters, such as the ..pi../N and K/N ratios at high kinetic energy, will survive the collision; therefore, a determination of the asymptotic form of the hadron spectrum probably can be made by studying nuclear collisions at very high energies (10 GeV/nucleon in the center of mass). 16 figures. (RWR)
Date: May 1, 1979
Creator: Glendenning, N.K.
Partner: UNT Libraries Government Documents Department

Heavy quark jets

Description: The present understanding of heavy quark fragmentation is reviewed, and the expected behaviors of heavy quark jets is discussed. Included are short-distance versus long-distance parts of fragmentation, fragmentation dynamics at long distances, universal hadronization in rapidity plot, the heavy quark as a sizzling fireball, quantum chromodynamics ladder summation in the region of K/sub T/ < ..lambda.., and the relevance or irrelevance to super high energy experiment. 6 references. (JFP)
Date: November 12, 1979
Creator: Suzuki, M.
Partner: UNT Libraries Government Documents Department

Relativistic heavy ion reactions

Description: The present status of the study of central collisions of relativistic heavy ions is presented. The phenomenology is described, and evidence is presented for a source of nucleons from a central region caused by the overlapping densities of the target and projectile. Some of the current theoretical approaches are described including the nuclear fireball model. It appears that there is a quasi-equilibrated region at high temperature, but the signature for the expected effects of high density is not yet clear, and therefore, experimentally, the effects of high density have not been identified.
Date: August 1, 1977
Creator: Poskanzer, A.M.
Partner: UNT Libraries Government Documents Department

Research in theoretical physics. Annual report, April 1, 1980-March 31, 1981

Description: Progress is reported on non-perturbative QCD at finite temperatures and on minimal subconstituent models of quarks and leptons. Following earlier conjectures, we the transition from weak to strong coupling in QCD is assumed to be accompanied by a phase transition in bulk hadronic matter; such a phase transition can be observed in fireballs formed in central collisions of heavy nuclei. The phase of the hadronic matter can perhaps be probed through leptonic reaction channels. In order to explore this conjecture, a simplified theory of the evolution of the fireball was developed. The main result is that just below a phase transition, increased fluctuations should give rise to increased radiation of direct photons, whereas above the phase transition, quark pairs annihilating into lepton pairs give a characteristic signature in that channel. The group structure of some minimal subconstituent models of quarks and leptons has been analyzed. The Lorentz structure of the subconstituents affects substantially the spectrum of such models. Within the conventional framework of field theory, two no-go theorems can be proved. The Harari-Shupe model does not contain the color and the weak interactions groups. An extended Harari-Shupe mode can incorporate color and contains W-bosons as composite objects; however, current algebra results are not reproduced in such models.
Date: December 1, 1980
Partner: UNT Libraries Government Documents Department

Comparison of models of high energy heavy ion collision. [0. 1 to 2. 0 GeV/nuo, review]

Description: Some of the main theoretical developments on heavy ion collisions at energies (0.1 to 2.0) GeV/nuc are reviewed. The fireball, firestreak, hydrodynamic (1-fluid, 2-fluids), ''row on row'', hard sphere and intranuclear cascades, and classical equations of motion models are discussed in detail. Results are compared to each other and to measured Ne + U ..-->.. p + X reactions.
Date: October 1, 1977
Creator: Gyulassy, M.
Partner: UNT Libraries Government Documents Department

Interactions of 100 MeV/nucleon /sup 40/Ar with uranium

Description: Fragments produced in the interactions of 100 MeV/nucleon /sup 40/Ar projectiles with a uranium target were measured at energies from 10 to 130 MeV/nucleon at angles from 10 to 170/sup 0/. Nuclei with charge 5 less than or equal to Z less than or equal to 10 were observed. The data can roughly be divided into two groups, corresponding to central and pripheral collisions. The central collision data can be fit with a thermal model that uses two recoiling sources. The source velocities are consistent with predictions of the fireball and target explosion models, but the source temperatures inferred from the data are higher than one would expect on the basis of energy and momentum conservation. These results are similar to those obtained in previous studies at beam energies of 400 and 500 MeV/nucleon. The data also follow the pattern of a universal curve of invariant cross section vs momentum. The projectile fragmentation data are also fit by two thermal sources. There are indications that the observed temperatures are higher than one would expect on the basis of other projectile fragmentation studies. The projectile fragmentation data are studied in terms of a simple friction model. Order-of-magnitude estimates show that the data may be consistent with the model, but further development, calculation, and experimentation are necessary to check the validity of the model at this beam energy. A preliminary investigation is made of the possibility that the projectile may pick up one or more target nucleons before it fragments. This process leads to widening of the distributions at large momentum transfers. Much of the spectrum can be described by falling exponentials in energy in the emitting frames. It is concluded that the observed spectrum is due to nonthermal sources as the temperatures derived from the slopes of the exponentials are greater ...
Date: December 1, 1979
Creator: Frankel, K.A.
Partner: UNT Libraries Government Documents Department

Incomplete and complete fusion in intermediate energy heavy ion reactions

Description: The yields, angular distributions and differential range spectra have been measured for individual target residues from the interaction of 8.5 MeV/A /sup 16/O, 19 MeV/A /sup 16/O, 35 MeV/A /sup 12/C and 86 MeV/A /sup 12/C with /sup 154/Sm. From the measured data, fragment isobaric yields and velocity spectra were deduced. The results are compared to the sum rule model of Wilczyski et al. and the nuclear firestreak model. 18 references.
Date: March 1, 1984
Creator: Aleklett, K.; Loveland, W.; Sugihara, T.T.; Morrissey, D.J.; Wenxin, L.; Kot, W. et al.
Partner: UNT Libraries Government Documents Department

Thermal models of ultrarelativistic heavy ion collisions

Description: Single-particle pseudorapidity, rapidity and transverse momentum distributions of secondaries produced in nucleus-nucleus central collisions at 14.6 and 200 A GeV are analyzed using the isotropic fireball, Boltzmann and hydrodynamical models. Calculations using a transverse hydrodynamical model with a first order phase transition in the equation of state from quark-gluon plasma to final state hadrons are compared to experimental transverse momentum spectra. 15 refs., 6 figs.
Date: October 1, 1990
Creator: Von Gersdorff, H.
Partner: UNT Libraries Government Documents Department

Intermediate- and high-energy reactions of uranium with neon and carbon

Description: Target fragment production from the interactions of 1.0, 3.0, 4.8, and 12 GeV /sup 12/C and 5.0, 8.0, 20, and 42 GeV /sup 20/Ne with uranium has been measured using off-line gamma-ray spectroscopic techniques. The experimental charge and mass yield distributions are generally consistent with the concepts of limiting fragmentation and factorization at energies of 3.0 GeV and above. The total projectile kinetic energy was found to be the relevant scaling parameter for the comparison of reactions induced by projectiles of different sizes. Light fragments with mass number less than 60 were found to violate limiting fragmentation, and had excitation functions that were strongly increasing with projectile energy until 8.0 to 12.0 GeV. With the 1.0 GeV /sup 12/C beam the pattern of mass yields was quite different from that of all the other reactions, with the normal peak in the fission mass region (80 < A < 145), but with much lower yields below mass number 60 and between mass numbers 145 and 210, indicating that these fragments are formed primarily in very energetic reactions in which large excitation energies are transferred to and significant amounts of mass are removed from the target nucleus. Theoretical predictions of the intra-nuclear cascade, nuclear fireball, and nuclear firestreak models are compared with the experimental results. The intra-nuclear cascade and nuclear firestreak models are both able to predict the general shapes of the experimental distributions, with the exception of the yields for the lightest fragments.
Date: November 1, 1982
Creator: McGaughey, P.L.
Partner: UNT Libraries Government Documents Department

A fresh look at Bose-Einstein correlations

Description: Recent experimental data on Bose-Einstein (BE) correlations between identical bosons are reviewed, and new results concerning the interpretation of the BE enhancement are discussed. In particular, it is emphasized that the classical interpretation of the correlation function in terms of the space-time distribution of particle production points cannot be directly applied to particle production in high energy reactions.
Date: March 1, 1987
Creator: Hofmann, W.
Partner: UNT Libraries Government Documents Department