Projectile Nucleons Research Articles

Studies of fast protons produced in the reactions of 16O Nuclei incident on emulsion nuclei at 3.7A GeV

• The grey particle multiplicity characteristics, reflects the role of the limiting fragmentation hypothesis. • It is found that the multiplicity distribution of grey particle is independent of the projectile energy or its size. • The multiplicity distribution P(Ng) of the emitted g-particles fit well with the Gauss distribution function, which is both symmetric and platykurtic behavior. Both values of Skewness (S) and Kurtasis (K) are less than zero. • The experimental data shows that the selectivity of N h particle multiplicity as an indication of the impact parameter of nuclear interaction is better than the choice of charged projectile spectator nucleons Q in each event. We report the experimental data of the fast target protons produced in the reaction of 16 O-Em at 3.7A GeV. The emission mechanism of the fast target protons (grey particles with kinetic energy in the range of 26 – 400 MeV) is investigated in terms of multiplicity characteristics. Our experimental data is compared with the corresponding data from the interactions of 12 C, 22 Ne and 28 Si projectiles at nearly the same incident energy. It is found that the multiplicity distribution is independent of the projectile energy or its size. The interaction events were classified in two ways. First, according to the degree of their centrality, depending on the number of the nucleons remaining as spectators Q (stripping nucleons) from the projectile. The second way, the interactions are classified according to the target size (N h – parameter). At various groups of events, the higher moments of the multiplicity distributions were calculated statistically. The experimental data shows that the selectivity of N h particle multiplicity as an indication of the impact parameter of nuclear interaction is better than the choice of charged projectile spectator nucleons Q in each event.

Nuclear Fusion Research and Development Need New Relativistic Mass and Energy Corrections Given by the Information Relativity Theory

Hundred years after the conjecture of the British astronomer Eddington that the sun is powered by nuclear fusion of hydrogen, new physics theory may help make energy harvesting by nuclear fusion soon a reality. Researchers as well as investors funding fusion megaprojects are asked to deal with new relativistic corrections for mass and energy proposed by Suleiman in his Information Relativity Theory (IRT). These corrections were calculated in this contribution. It will help to decide whether a venture will be successful and to save big investments when in doubt. The assumed optimal kinetic energy for controlled nuclear fusion must be corrected to a somewhat higher level. At very high kinetic energy in the upper GeV range, it remains not enough baryonic mass to be transformed in energy. The fusion probability faded out to zero already at the golden limit of the recession speed of between target nucleon and projectile nucleon. Cold nuclear fusion, if ever possible, is recommended for protons rather than deuterons at highest experimental possible temperatures around 1000 (K) and needs fine-tuned kinetic nucleon energy. It would be also of interest whether a golden ratio based nuclear fuel confinement chamber could be beneficial. In this connection, also cold nuclear fusion setups should be discussed. Nature is governed by the golden ratio and criticality of physical systems influenced by it, and nuclear physics is not an exception. Computer simulations of the underlying controlled nuclear fusion processes should gain profit from IRT corrected starting information and may tackle anew possible low energy nuclear transmutations considering the wave-like dark components of matter and energy.

Multiplicity characteristics of target fragments and shower particles with noninteracting projectile nucleons emitted in 84Kr–Em interaction at 1 A GeV

In this article, we have focused on the multiplicity distributions of the target fragments and shower particles for the events released from the interactivity of the 84 Kr36 –Em at 1 A GeV. We have also focused on the variation among the target fragments and shower particles with emerged projectile fragments. In the present analysis to distinguish the type of collision, we have used different parameter which is total charge Q of the outgoing projectile fragments (i.e. the projectile fragments emitted in forward cone θ c ≤ 30 ) or total charge of noninteracting projectile nucleons, in place of impact parameter. This new parameter is playing an important role in classifying the different types of collisions, especially in peripheral collisions. The results of the current analysis are also verified with recent experimental observations and found to be consistence.

Comparison between the elastic scattering of 12C(α,α)12C and 12C(6He, 6He)12C using different nuclear potentials

The experimental angular distributions for [Formula: see text]-particles elastically scattered from [Formula: see text]C nucleus in the energy range 48.7–386[Formula: see text]MeV and for 6He+[Formula: see text]C nuclear system in the energy range 5.9–493.8[Formula: see text]MeV have been reanalyzed. Data analysis is performed within the framework of both optical model (OM) and double folding optical model (DFOM). In this model, the real part of the potential is generated using the double folding procedures based on the effective M3Y interaction between projectile nucleons and target nucleons in addition to an imaginary part of Woods–Saxon (WS) form. Two criteria are used in order to observe the nature of 4He and 6He elastically scattered from [Formula: see text]C and the effect of the two neutron halo structure of 6He. First, the extracted potential parameters are utilized for calculating the reflexion coefficients [Formula: see text] which is strongly related to angular momentum [Formula: see text]. Second, the reduction in reaction cross-sections with the projectile’s energy.

The multiplicity characteristics of7Li-Em interactions as a function of noninteracting projectile nucleons

In this work, the interactions of7Li nuclei with emulsion at 3 A GeV/c were studied. Multiplicity of the charged secondary particles as well as the charge of the outgoing projectile fragments were measured, while correlations among them are discussed. The values of the total charge of the noninteracting projectile nucleons and the average number of interacting projectile nucleons are estimated. The dependence of the secondary particles on the number of heavily-ionized tracks is analyzed. The results show that interactions of7Li nuclei with emulsion nuclei exhibit a number of regularities, which had been noted in experiments with lighter nuclei. The absorption of relativistic particles, while increasing the degree of target destruction, is observed. The average multiplicities of the secondary charged particles depend on the impact parameter, as their values increase, while decreasing the impact parameter. The number of secondary charged particles in the heavy-ion interactions depends on the degree of disintegration of the target nuclei. This dependence is not observed in the case of the interaction of hadron with emulsion. The experimental data of the interaction of7Li are systematically compared with the other interactions at different energies. The results agree with the corresponding results at nearly the same energy.

The very forward hadron calorimeter PSD for the future CBM@FAIR experiment

The Projectile Spectator Detector (PSD) of the CBM experiment at the future FAIR facility is a compensating lead-scintillator calorimeter designed to measure the energy distribution of the forward going projectile nucleons and nuclei fragments (reaction spectators) produced close to the beam rapidity. The detector performance for the centrality and reaction plane determination is reviewed based on Monte-Carlo simulations of gold-gold collisions by means of four different heavy-ion event generators. The PSD energy resolution and the linearity of the response measured at CERN PS for the PSD supermodule consisting of 9 modules are presented. Predictions of the calorimeter radiation conditions at CBM and response measurement of one PSD module equipped with neutron irradiated MPPCs used for the light read out are discussed.

Benchmark of neutron production cross sections with Monte Carlo codes

Abstract Aiming to provide critical information in the fields of heavy ion therapy, radiation shielding in space, and facility design for heavy-ion research accelerators, the physics models in three Monte Carlo simulation codes – PHITS, FLUKA, and MCNP6, were systematically benchmarked with comparisons to fifteen sets of experimental data for neutron production cross sections, which include various combinations of 12C, 20Ne, 40Ar, 84Kr and 132Xe projectiles and natLi, natC, natAl, natCu, and natPb target nuclides at incident energies between 135 MeV/nucleon and 600 MeV/nucleon. For neutron energies above 60% of the specific projectile energy per nucleon, the LAQGMS03.03 in MCNP6, the JQMD/JQMD-2.0 in PHITS, and the RQMD-2.4 in FLUKA all show a better agreement with data in heavy-projectile systems than with light-projectile systems, suggesting that the collective properties of projectile nuclei and nucleon interactions in the nucleus should be considered for light projectiles. For intermediate-energy neutrons whose energies are below the 60% projectile energy per nucleon and above 20 MeV, FLUKA is likely to overestimate the secondary neutron production, while MCNP6 tends towards underestimation. PHITS with JQMD shows a mild tendency for underestimation, but the JQMD-2.0 model with a modified physics description for central collisions generally improves the agreement between data and calculations. For low-energy neutrons (below 20 MeV), which are dominated by the evaporation mechanism, PHITS (which uses GEM linked with JQMD and JQMD-2.0) and FLUKA both tend to overestimate the production cross section, whereas MCNP6 tends to underestimate more systems than to overestimate. For total neutron production cross sections, the trends of the benchmark results over the entire energy range are similar to the trends seen in the dominate energy region. Also, the comparison of GEM coupled with either JQMD or JQMD-2.0 in the PHITS code indicates that the model used to describe the first stage of a nucleus-nucleus collision also affects the low-energy neutron production. Thus, in this case, a proper combination of two physics models is desired to reproduce the measured results. In addition, code users should be aware that certain models consistently produce secondary neutrons within a constant fraction of another model in certain energy regions, which might be correlated to different physics treatments in different models.

Peculiarities in total cross sections of reactions with weakly bound nuclei 6He, 9Li

The energy dependence of the total cross sections for the 6He + Si and 9Li + Si reactions was measured at beam energies between 5 and 20 MeV per nucleon. The results agree with experimental data published for the 6He + Si reaction. New data are obtained for the 9Li + Si reaction in the vicinity of a local enhancement of the total cross section. A theoretical analysis of the possible reasons behind the appearance of this peculiarity in the case of collisions of 6He and 9Li nuclei with silicon target nuclei is performed. In particular, the enhancement may owe its origin to the effect of loosely bound projectile nucleons.

Consequences of high-xproton size fluctuations in small collision systems atsNN=200GeV

Recent measurements of jet production rates at large transverse momentum ($p_T$) in the collisions of small projectiles with large nuclei at RHIC and the LHC indicate that they have an unexpected relationship with estimates of the collision centrality. One compelling interpretation of the data is that it captures an $x_p$-dependent decrease in the average interaction strength of the nucleon in the projectile undergoing a hard scattering. A weakly interacting or "shrinking" nucleon in the projectile strikes fewer nucleons in the nucleus, resulting in a particular pattern of centrality-dependent modifications to high-$p_T$ processes. We describe a simple one-parameter geometric implementation of this picture within a modified Monte Carlo Glauber model tuned to $d$$+$Au jet data, and explore two of its major consequences. First, the model predicts a particular projectile-species dependence to the centrality dependence at high-$x_p$, opposite to that expected from an energy loss effect. Second, we find that some of the large centrality dependence observed for forward di-hadron production in $d$$+$Au collisions at RHIC may arise from the physics of the "shrinking" projectile nucleon, in addition to impact parameter-dependent shadowing or saturation effects at low nuclear-$x$. We conclude that analogous measurements in recently collected $p$$+$Au and $^3$He$+$Au collision data at RHIC can provide a unique test of these predictions.

Jets and Centrality in p(d)-A Collisions

The production of jets, and high-pT leading pions from jets, in d-Au collisions at the Relativistic Heavy-Ion Collider (RHIC) and p-Pb collisions at the Large Hadron Collider (LHC) are studied. Using a modified version of the event generator PYTHIA, in conjunction with a nuclear Glauber Monte-Carlo event generator, we demonstrate how events with a hard jet may be simulated, in such a way that the parton distribution function of the projectile nucleon is frozen during its interaction with the extended nucleus. Using our hybrid Monte-Carlo event generator, we demonstrate that the enhancement in RpA seen in peripheral events at RHIC and at LHC, as well as the depletion in central or semi-central events, is mainly due to “mis-binning” of central and semi-central events with a jet, as peripheral events. This occurs due to the reduction of soft particle production caused by a depletion of energy available in a nucleon (of the deuteron in the case of d-Au collisions), after the production of a hard jet. This represents a form of “color transparency” of the projectile nucleon, which has fluctuated to a state with fewer and harder partons, in events which lead to jet production. We conclude with discussions of the form of multi-parton correlations in a nucleon which may be responsible for such a startling effect.

Extracting squared speed-of-sound parameter from asymmetric nuclear collisions at high energies

We apply the Landau hydrodynamic model in leading target/projectile nucleons and target/projectile cylinders in the multisource thermal model respectively, in asymmetric nuclear collisions. Each leading nucleon source or cylinder source is regarded as an energy reservoir to emit or produce particles and can be described by the Landau hydrodynamic model. The pseudorapidity distribution of final-state particles is in fact a sum of four Gaussian functions which correspond to the contributions of the leading target nucleons, target cylinder, projectile cylinder and leading projectile nucleons, respectively, in accordance with their central rapidities from low to high value. Based on the descriptions of the pseudorapidity distributions of final-state particles produced in proton-emulsion, deuteron-gold and gold-emulsion collisions, the squared speed-of-sound parameters for the four sources in asymmetric nuclear collisions have been extracted and shown to be approximately the same within the statistical error.

Generation of high-energy neutron beam by fragmentation of relativistic heavy nuclei

The phenomenon of multiple production of neutrons in reactions with heavy nuclei induced by high-energy protons and light nuclei is analyzed using a Moving Source Model. The Lorentz transformation of the obtained neutron distributions is used to study the neutron characteristics in the inverse kinematics where relativistic heavy nuclei bombard a light-mass target. The neutron beam generated at 0[Formula: see text]has a Gaussian shape with a maximum at the energy of the projectile nucleons and an energy resolution [Formula: see text]/[Formula: see text] above 6 GeV.

Forward physics with the LHCf experiment: a LHC contribution to cosmic-ray physics

LHCf is a small detector installed at LHC accelerator to measure neutral par- ticle flow in the forward direction of proton - proton (p - p) and proton - nucleus (p - A) interactions. Thanks to the optimal performance that has characterized the last years' running of the LHC collider, several measurements have been taken since 2009 in differ- ent running conditions. After data taking for p - p interactions at √ s = 900 GeV, 2.76 TeV and 7 TeV and proton - Lead nucleus (p - Pb) at √ sNN = 5.02 TeV (energy of a couple of projectile and target nucleons in their center of mass reference frame), LHCf is now going to complete its physics program with the 13 TeV p - p run foreseen in 2015. The com- plete set of results will become a reference data set of forward physics for the calibration and tuning of the hadronic interaction models currently used for the simulation of the atmospheric showers induced by very high energy cosmic rays. For this reason we think that LHCf is giving an important contribution for the study of cosmic rays at the highest energies. In this paper the experiment, the published results and the current status are reviewed.

Pion cross section parameterizations for space radiation codes

The space radiation environment consists of energetic particles that originate from the Sun and from sources outside the solar system. It is necessary to understand how these particles interact with materials to design effective radiation shielding. The transport of radiation through materials can be described by the Boltzmann equation. Efficient space radiation transport codes often require parameterized energy-dependent spectral distributions. A recent study showed that pions may contribute considerably to the total dose in galactic cosmic ray environments. Consequently, accurate parameterized pion spectral distributions are needed. In other studies, the Badhwar parameterization has been used for inclusive pion production in high energy nucleon–nucleon and nucleon–nucleus collisions, whereas a thermal model has been used to describe pion production in low energy nuclear collisions. In this paper, the thermal model is parameterized in terms of projectile energy, projectile nucleon number, and target nucleon number. Thermal and Badhwar model predictions of pion spectra from nucleon–nucleus and nucleus–nucleus collisions are compared for projectile energies ranging from 0.3 to 158AGeV. It is recommended that the thermal model be used for projectile energies between 0.4 and 5AGeV and the Badhwar model be used for higher projectile energies.

Dynamics of large Ar cluster bombardment of organic solids

Molecular dynamics computer simulations are used to investigate the ejection process of molecules from a benzene crystal bombarded with keV large Ar clusters. The effect of projectile size, the kinetic energy and the impact angle on the sputtering efficiency is investigated. The results show that although the sputtering yield depends on all projectile parameters, this dependence can be greatly simplified if the sputtering yield per projectile nucleon is expressed as a function of projectile kinetic energy per nucleon. A different dependence of the total sputtering yield on the impact angle has been observed for small and large projectiles. This effect is attributed to a ‘washing out’ mechanism. For large projectiles most of the organic molecules are ejected by gentle collective action of argon atoms. Proper selection of the projectile parameters allows for achieving conditions where only intact molecules are emitted. Copyright © 2012 John Wiley & Sons, Ltd.

Microscopic study of deuteron–nucleus total reaction cross section at medium energies

Total reaction cross sections for 38, 67 and 97 MeV deuteron for several nuclei have been analyzed within the theoretical framework of the Glauber model. The Glauber elastic S-matrix element to the deuteron–nucleus system is evaluated in the rigid projectile model which takes as the input N–d elastic scattering amplitude evaluated in terms of the nucleon–nucleon amplitude and ground state density of the deuteron. The analysis takes into consideration the Coulomb modification of the projectile trajectory, downward energy shift of the projectile nucleon due to the Coulomb field and the modification on nucleon–nucleon total cross section. The contribution to the total reaction cross section from the photo-disintegration of the deuteron is also considered. Using the semi-phenomenological proton and neutron densities for the target, we find that in general, the theoretical predictions are in fairly good agreement with the experimental data.

Bremsstrahlung from relativistic heavy ions in matter

The emission of electromagnetic radiation by relativistic bare heavy ions penetrating ordinary matter is investigated. Our main aim is to determine the bremsstrahlung which we define as the radiation emitted when the projectile does not break up. It pertains to collisions without nuclear contact ('ultraperipheral collisions'). Requirement of coherent action of the nucleons in order to keep the penetrating projectile intact limits bremsstrahlung to relatively soft photons. The spectrum shows a resonance structure with peak position near 2{gamma} times the position of the giant dipole resonance, that is, near 25{gamma} MeV for a lead ion ({gamma}{identical_to}E/Mc{sup 2} is the Lorentz factor of the projectile of energy E and mass M). The maximum exceeds the bremsstrahlung from a hypothetical structureless, pointlike particle of the same charge and mass as the incoming nucleus, but rapid depletion follows on the high-energy side of the peak. As a result of its relative softness, bremsstrahlung never dominates the energy-loss process for heavy ions. As to the emission of electromagnetic radiation in collisions with nuclear break-up, it appears modest when pertaining to incoherent action of the projectile nucleons in noncontact collisions. In collisions with nuclear contact, though, substantial radiation is emitted. It overshoots the bremsstrahlung. However, more » despite the violence of contact events, the associated photon emission only exceeds the radiation from a hypothetical structureless pointlike nucleus [emitted energy per unit photon-energy interval essentially constant up to ({gamma}-1)Mc{sup 2}] at relatively low photon energies (for lead roughly below 0.2{gamma} GeV, a limit which is about an order of magnitude above the position of the bremsstrahlung peak). Results are presented for bare lead ions penetrating a solid lead target at energies of 158 GeV/n ({gamma}=170) and beyond. « less

Global quark polarization in noncentralA+Acollisions

Partons produced in the early stage of noncentral heavy-ion collisions can develop a longitudinal fluid shear because of the unequal local number densities of participant target and projectile nucleons. Under such fluid shear, local parton pairs with nonvanishing impact parameters have finite local relative orbital angular momentum along the direction opposite to the reaction plane. Such a finite relative orbital angular momentum among locally interacting quark pairs can lead to global quark polarization along the same direction because of spin-orbital coupling. Local longitudinal fluid shear is estimated within both the Landau fireball and the Bjorken scaling model of initial parton production. Quark polarization through quark-quark scatterings with the exchange of a thermal gluon is calculated beyond the small-angle scattering approximation in a quark-gluon plasma. The polarization is shown to have a nonmonotonic dependence on the local relative orbital angular momentum dictated by the interplay between electric and magnetic interactions. It peaks at a value of relative orbital angular momentum which scales with the magnetic mass of the exchanged gluons. With the estimated small longitudinal fluid shear in semiperipheral Au+Au collisions at energies currently available at the BNL Relativistic Heavy Ion Collider (RHIC), the final quark polarization is found to be small $|{P}_{q}|<0.04$ in the weak coupling limit. Possible behavior of the quark polarization in the strong coupling limit and implications on the experimental detection of such global quark polarization at RHIC and CERN Large Hadron Collider (LHC) are also discussed.

The possibility of time resonance (explosion) phenomena in high-energy nuclear reactions

Abstract This study shows that the exponential decrease of the energy spectra, accompanied by slight oscillations, with final-fragment energy in high-energy nuclear reaction, and independent of fragments, targets, projectiles, and projectile energies, can be explained under some conditions in the range of strongly overlapping compound resonances by a new phenomenon of time resonances (explosions). These time resonances (explosions) correspond to the formation of a few highly-excited, non-exponentially decaying nuclear clots (partial compound nuclei consisting of certain small groups of target and projectile nucleons). The proposed approach is an alternative way of analyzing experimental data compared with the majority of known descriptions (for instance, fireball models). This is a new and more general version of the time-evolution approach compared with the Izumo-Araseki time compound-nucleus model.

Role of antisymmetrization in describing the excitation of the 1+, T = 1 level in the 12C nucleus by polarized protons

Inelastic polarized-proton scattering involving the excitation of the 1+, T = 1 level at 15.11 MeV in the 12C nucleus is described within the distorted-wave method. The effect of completely or approximately taking into account the antisymmetrization of the wave function for the projectile proton-intranuclear nucleons system on various observables, including the differential reaction cross section, the analyzing power, the difference of the polarization and analyzing power, and the depolarization parameter, is analyzed. The difference of the polarization and the analyzing power in the case of the excitation of anomalous-parity levels is shown to be especially sensitive to taking into account the above antisymmetrization. The reason for a large value of this difference for the level being studied and the sensitivity of this value to the parameters of the effective nucleon-nucleon interaction used are analyzed.