Search for highly charged particles in cosmic rays

The recently obtained results on e⁺e^? → hadrons and multigamma production in pp collisions provide some support for a previously made argument that heavy, highly charged subnucleons may exist, and a search for such particles in cosmic rays has been made. In 620 hours no candidates were detected, and an upper limit for the unaccompanied particle flux of 7 · 10^?10 cm^?2 sec^?1 sr^?1 at sea level under 600 g/cm² concrete is obtained with 90% confidence.     

Unstable superheavy relic particles as a source of neutrinos responsible for ultrahigh-energy cosmic rays

Decays of superheavy relic particles may produce extremely energetic neutrinos. Their annihilations on the relic neutrinos can be the origin of the cosmic rays with energies beyond the Greisen-Zatsepin-Kuzmin cutoff. The redshift acts as a cosmological filter selecting the sources at some particular value z(e)+/-deltaz, for which the present neutrino energy is close to the Z pole of the annihilation cross section. We predict no directional correlation of the ultrahigh-energy cosmic rays with the galactic halo. At the same time, there can be some directional correlations in the data, reflecting the distribution of matter at redshift z = z(e)+/-deltaz. Both of these features are manifest in the existing data. Our scenario is consistent with the neutrino mass reported by super-Kamiokande and requires no lepton asymmetry or clustering of the background neutrinos.     

Non-thermal dark matter,high energy cosmic rays and late-decaying particles from inflationary quantum fluctuations

It has been suggested that the origin of cosmic rays above the GZK limit might be explained by the decay of particles, X, with mass of the order of 10¹² GeV. Generation of heavy particles from inflationary quantum fluctuations is a prime candidate for the origin of the decaying X particles. It has also been suggested that the problem of non-singular galactic halos might be explained if dark matter originates non-thermally from the decay of particles, Y, such that there is a free-streaming length of the order of 0.1 Mpc. Here we explore the possibility that quantum fluctuations might account for the Y particles as well as the X particles. For the case of non-thermal WIMP dark matter with unsuppressed weak interactions we find that there is a general problem with deuterium photo-dissociation, disfavouring WIMP dark matter candidates. For the case of more general dark matter particles, which may have little or no interaction with conventional matter, we discuss the conditions under which X and Y scalars or fermions can account for non-thermal dark matter and cosmic rays. For the case where X and Y scalars are simultaneously produced, we show that galactic halos are likely to have a dynamically significant component of X scalar cold dark matter in addition to the dominant non-thermal dark matter component.     

Multidetector device for the detection of coincidences of charged particles and γ rays

A 4π position-sensitive, axisymmetrical assembly of Si-Au charged-particle detectors is proposed, implemented, and tested on a beam of heavy ions; the dimensions and structure of the device are conducive to the organization of coincidences of charged reaction products with discrete γ rays emitted by the daughter nucleus and registered by a system of ultrapure Ge detectors. First results are obtained from an investigation of the reaction ⁵⁸Ni(¹⁶O,α2pγ)⁶⁸Ge at E ₀=74.5 MeV. Zh. Tekh. Fiz. 68, 139–142 (April 1998)     

Absorbed dose from galactic cosmic rays and solar protons as derived from stratospheric measurements

Regular measurements of charged-particle fluxes in the Earth’s atmosphere, performed at the Lebedev Institute of Physics, Russian Academy of Sciences since 1957 up to date, are used to determine the absorbed dose rate in the atmosphere from galactic cosmic rays in the period of minimum solar activity and from solar protons during solar proton events. The values of the absorbed dose rate estimated from the measurement data for some intense solar proton events are reported.     

High-energy gamma rays emission in coincidence with light charged particles from the32S +74Ge reaction at 210 MeV

High-energyγ-rays from the³²S+⁷⁴Ge reaction at 210 MeV bombarding energy were measured in coincidence with light charged particles detected in a large area hodoscope. Experimental results show that energeticγ-rays in coincidence with light charged particles are essentially emitted in the compound nucleus decay. The parameters of the giant dipole resonance (GDR) have been extracted from alineshape analysis of the experimentalγ-ray spectrum. The derived values of mean energyE _D, widthΓ and strengthS are in good agreement with results from previous experiments on Sn isotopes obtained by using different experimental techniques.     

带电粒子与磁化等离子体相互作用的极化效应及能量损失

 利用线性Vlasov-Poisson方程,研究了带电粒子在磁化二份量等离子体中运动时产生的动力学极化效应及能量损失,重点分析了外磁场及等离子体中离子的极化效应对入射粒子能量损失响。数值结果表明：入射粒子的能量损失有两个峰,分别位于高速区和低速区,对应于等离子体中的电子极化效应和离子极化效应。在强磁场情况下,低速粒子的能量损失主要来自离子的极化效应;而在弱磁场情况下,高速粒子的能量损失则主要来自于电子的极化效应。     

阵列式康普顿相机GEANT4模拟与图像重建及优化

出于对放射性核素各种应用和安全的考虑,需要性能良好的康普顿相机。通过蒙特卡罗方法模拟了双层阵列式康普顿相机,散射探测器材料为Si,吸收探测器材料为CZT（碲锌镉）。利用反投影图像重建算法进行了图像重建,采用极大似然法对重建结果进行优化,有效地提高了重建图像的分辨率。当放射源与探测器距离100 mm时,经过10次极大似然法迭代计算,位置分辨率与角分辨率分别达到5.1 mm与7.3。检验了极大似然法对于康普顿相机放射源图像重建的优化作用。     

Exploration of a possible cumulative action of the zero-point field on intergalactic particles and implications for cosmic rays and a X-ray background from the intergalactic medium

Summary The intergalactic space (IGS) has ideal conditions to test the weak but cumulative action that the electromagnetic (EM) zero-point field (ZPF) of ordinary quantum theory (QT), if conceived as a real field, may have on EM interacting particles. Recent results (classical stochastic and quantum) indicate that if the EM ZPF of ordinary QT is conceptually assimilated to a real random field, electrically polarizable particles perform a random walk in velocity space to ever-increasing translational kinetic energies. As the ZPF has a Lorentz-invariant energy density spectrum, statistically it keeps the same form and is homogeneous and isotropic in all inertial frames of reference. No velocity-dependent forces can hence appear on particles moving through the ZPF. Acceleration is thus possible in a high vacuum. The hierarchy of dissipation mechanisms for the accelerated ultrarelativistic protons in the IGS is established in detail. In the IGS outside superclusters cosmic expansion is the most significant dissipation mechanism. The previously derivedE ^−η particle energy spectrum is obtained except for a cut-off: cosmic expansion puts a drastic cut-off to the energy spectrum of ZPF accelerated particles in the IGS out-side clusters or superclusters. This cut-off does not appear for CR primaries confined to the magnetic cavities of clusters or superclusters. When this confinement is effective, the ZPF acceleration may still be as relevant a CR acceleration mechanism as previously contended. The possible relevance of the ZPF in energizing the intergalactic medium (IGM) is briefly discussed. As it has recently been shown that electrons are not accelerated by the ZPF, electrons can only receive energy from the proton component of the IGM plasma and should display an approximately Maxwellian distribution. This could not occur, would electrons absorb energy directly from the ZPF. In that case they would display the Lorentz-invariant distribution. The electron component loses energy mainly by thermal bremsstrahlung or by inverse Compton collisions with the 2.7 K photons depending on the assumed number density of IGS electrons. The X-ray emission of the proton component can be dismissed in comparison with that of the electrons, despite the usual higher energies of protons in their distribution which is not Maxwellian. The relevance of the ZPF acceleration model for explaining the observed X-ray background is preliminarily discussed. The inherent thermodynamic limitations of the model are also briefly outlined.

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Riassunto Lo spazio intergalattico (IGS) ha condizioni ideali per provare l'azione debole ma cumulativa che il campo elettromagnetico (EM) del punto zero (ZPF) della normale teoria quantica (QT), se considerato come campo reale, può avere su particelle interagenti EM. Risultati recenti (classci stocastici e quantici) indicano che se lo ZPF EM della normale QT è assimilato concettualmente a un campo reale causuale, particelle elettricamente polarizzabili effettuano un percorso casuale nello spazio delle velocità a energie cinetiche traslazionali in continuo aumento. Poiché lo ZPF ha uno spettro di densità dell'energia invariante secondo Lorentz, statisticamente mantiene la stessa forma ed è omogeneo e isotropo in tutti i sistemi di riferimento inerziali. Nessuna forza dipendente dalla velocità può quindi apparire su particelle che si muovono nel ZPF. L'accelerazione è quindi possibile in un alto vuoto. La gerarchia dei meccanismi di dissipazione per i protoni ultrarelativistici accertati nell'IGS è stabilita dettagliatamente. Nell'IGS al di fuori dei superammassi l'espansione cosmica è il piú significativo meccanismo di dissipazione. Si ottiene lo spettro di energia delle particelleE ^η) precedentemente derivato tranne che per un taglio: l'espansione cosmica mette un taglio drastico nello spettro di energia delle particelle accelerate dallo ZPF nell'IGS all'esterno agli ammassi e ai superammassi. Questo taglio non compare per primari di CR confinati in cavità magnetiche di ammassi e superammassi. Quando questo confinamento è efficace, l'accelerazione del ZPF può ancora essere un meccanismo di accelerazione dei raggi cosmici cosí rilevante come precedentemente arguito. Si discute brevemente la possibile importanza dello ZPF nell'energizzare il mezzo intergalattico (IGM). Poiché è stato mostrato recentemente che gli elettroni non sono accelerati dallo ZPF, gli elettroni possono solo ricevere energia dalla componente protonica del plasma dell'IGM e dovrebbero mostrare una distribuzione approssimativamente maxwelliana. Questo non accadrebbe se gli elettroni assorbissero energia direttamente dallo ZPF. In quel caso mostrerebbero una distribuzione invariante secondo Lorentz. La componente elettronica perde energia principalmente attraverso bremsstrahlung termico, o attraverso collisioni di Compton inverse con i fotoni a 2.7 K a seconda della densità numerica degli elettroni IGS considerata. L'emissione di raggi X della componente protonica può essere trascurata in confronto con quella degli elettroni malgrado le usuali energie maggiori degli elettroni nella loro distribuzione che non è maxwelliana. Si discute preliminarmente l'importanza del modello di accelerazione dello ZPF per spiegare il sottofondo di raggi X osservato. Si delineano anche brevemente gl'inerenti limiti termodinamici del modello.

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Резюме Межгалактическое пространство обладает идеальными условиями для проверки слабого, но кумулятивного действия, которое может оказывать электромагнитное поле с нулевой точкой в обычной квантовой теории, если оно рассматривается как реальное поле, на частицы, взаимодействующие электромагнитным образом. Недавние результаты (классические стохастические и квантовые) показывают, что если злектромагнитное поле с нулевой точкой в обычной квантовой теории концептуально приравнивается реальному случайному полю, то электрически поляризуемые частицы соверщают случайные блуждания в скоростном пространстве, увеличивая трансляционную кинетическую знергию. Когда поле с нулевой точкой имеет Лоренц-инвариантный спектр плотности знергии, то статистически он сохраняет форму и является однородным и изотронным во всех инерциальных системах отсчета. Следовательно, на частицы, движущиеся через поле с нулевой точкой, не могут действовать силы, зависяшие от скорости. Поэтому оказывается возможным ускорение в глубоком вакууме. Подробно описывается иерархия механизмов диссипации для ускоренных ультрарелятивистских протонов в межгалактическом пространстве. В межгалактическом пространстве, вне суперкластеров, космическое расщирение представляет наиболее существенный механизм диссипации. Получается ранее выведенный энердетический спектр частиц, за исключением обрезания. Космическое расщирение накладывает сушественное обрезание на энергетический спектр частиц, ускоренных в поле с нулевой точкой, в междалактическом пространстве, вне кластеров или суперкластеров. Указанное обрезание не возникает для первичных космических лучей, удерживаемых в магнитных полостях кластеров или суперкластеров. Когда это удержание является эффективным, то ускорение полем с нулевой точкой может представлять возможный механизм ускорения космич=yeских лучей, как утверждалось ранее. Вкратце овсуждается роль поля с нулевой точкой в энергетике межгалактической среды. Как было недавно показано, что электроны не ускоряются полем с нулевой точкой, электроны могут только получать энергию от протонной компоненты плазмы межгалактической среды и должны обладать приблизительно максвелловским распределением. Это может не иметь место, тогда электроны могут поглощать энергию прямо из поля с нулевой точкой. В этом случае они обладают Лоренц-инвариантным распределением. Электронная компонента теряет энергию, в основном, за счет теплового тормозного излучения или обратного комптоновского соударения с протонами, имеющими температуру 2.7 К, в зависимости от предлагаемого числа электронов межгалактической среды. Рентгеновским излучением для протонной компоненты можно пренебречь по сравнению с излучением для электронов, несмотря на обычные высокие энергии протонов в распределении, которое не является максвелловским. Предварительно обсуждается уместность модели ускорения полем с нулевой точкой для обьяснения наблюденного фона рентгеновских лучей. Вкратце отмечаются специфические термодинамические ограничения предложенной модели.

     

Comparison of experimental data with predictions of various models for silicon and aluminum fragmentation under the effect of high-energy cosmic rays

The accuracy attained in theoretically estimating the yields of isotopes and isobars and their energy, charge, and mass distributions in silicon fragmentation that occurs in spacecraft electronics under the effect of cosmic-ray protons is an important factor in forecasting the probability for single-event upsets in the electronics and the reliability of spacecraft operation in general. In previous studies of our group, it was shown that the results of the calculations are highly sensitive to the choice of parameters for opticalmodel potentials. In addition to cross sections for elastic and inelastic proton scattering and charge, mass, and energy distributions of heavy nuclear-reaction products, the results of our calculations for doubledifferential spectra of protons originating from the interaction of highly energetic (30–400 MeV) protons with aluminum and double-differential spectra of other particles (neutrons and alpha particles) arising in competing channels of the p + ²⁷Al reaction are also described in the present article. The calculations in question were performed on the basis of the EMPIRE-II-19 code by using various optical-model potentials, including the Becchetti-Greenlees potential for the (p, n) channel, the Wilmore-Hodgson potential for the (p, n) channel, the Madland potential for the (p, p) channel, the Koning-Delaroche potential for the (p, p) channel, and the McFadden-Satchler potential for the (p, α) channel. A comparative analysis of the double-differential spectra obtained for outgoing protons, neutrons, and alpha particles experimentally and in the calculations of various authors was performed.     

Trigger and reconstruction for heavy long-lived charged particles with the ATLAS detector

Long lived charged particles are predicted by many models of physics beyond the standard model (SM). The common signature of such models is a heavy long-lived charged particle with velocity smaller than the speed of light, β<1. This unique signature makes the search for it model independent. This paper presents methods we developed as part of the ATLAS trigger and reconstruction chain for identifying slow particles and measuring their mass. The efficacy of these methods is demonstrated using two models that are different in every aspect except for the existence of long lived charged particles; a GMSB model that includes sleptons with a mass of 100 GeV, and R-Hadrons with a mass of 300 GeV produced in a split SUSY model.     

Experimental facilities for the TRD/ALICE tests with electron-pion beam and cosmic particles

Two special experimental facilities have been designed and produced to provide charged particle tests of the Transition Radiation Detector (TRD) prototypes and modules for the ALICE experiment at CERN. The first facility, comprising the scintillation and Cherenkov detectors, was applied for the TRD elements investigation with a secondary mixed electron-pion beam of the CERN proton synchrotron PS. The second one, consisting of two large-scale scintillation planes and original electronics, is under operation to trigger the 7-m long TRD supermodules on closing stand-alone trial with cosmic particles. The design and performance of both facilities are considered. The article is published in the original.     

Decay of giant resonances in light and medium-mass nuclei from coincidence experiments with charged particles

In recent years, the physics of electromagnetic interactions has made considerable advances in studying giant multipole resonances, which are highly excited collective states of nuclei. After the advent of new-generation continuous-beam accelerators, (e, e′x) coincidence experiments were performed, and new precision data on giant multipole resonances were obtained from these experiments. A number of examples of cross sections for decay accompanied by proton and alpha-particle emission in p-, sd-, and pf-shell nuclei of mass number in the range 16 ? A ? 64 are given. The relative contributions of these reactions are compared, their general and special features are revealed, and evaluations for semidirect and statistical decays are presented.     

Search for periodicities in galactic cosmic rays,sunspots and coronal index before arrival of relativistic protons from the sun

Using different approaches and techniques of wavelet analysis we analyze variations (oscillations) of galactic cosmic rays, solar spot number, and coronal index of solar activity before ground level enhancements of solar cosmic rays. Obtained results are discussed in frames of recent ideas about periodicity phenomena in the photosphere, and corona of the Sun, interplanetary medium, and cosmic rays.     

Study of the charge distribution of galactic cosmic rays and search for superheavy nuclei traces in olivine crystals from meteorites

The search for and identification of energetic nuclei of superheavy elements of cosmic rays in olivine crystals frommeteorites, currently performedwithin the Olympia project [1], are based on measurements of dynamic and geometrical parameters of tracks, i.e., chemically etchable regions of the traces of slowing down of these nuclei before their stop, using the fully automated PAVIKOM measuring system [2].     

Equations of motion from field equations and a gauge-invariant variational principle for the motion of charged particles

New, gauge-independent, second-order Lagrangian for the motion of classical, charged test particles is proposed. It differs from the standard, gauge-dependent, first-order Lagrangian by boundary terms only. A new method of deriving equations of motion from field equations is developed. When applied to classical electrodynamics, this method enables us to obtain unambiguously the above, second-order Lagrangian from the general energy-momentum conservation principle.     

Dispersion relations and low-energy elastic scattering of charged particles from nuclei: (II). Application to N-4He scattering

A “Coulomb-modified” dispersion relation is applied to low-energy p-⁴He forward elastic scattering. To check the validity of the modification, the results are compared with those deduced from n-⁴He elastic scattering. Completely analogous information is obtained for the two processes. The exchange of three bound nucleons is found to contribute strongly to N-⁴He forward scattering. The corresponding ⁴He-³H-p and ⁴He-³He-n coupling constants are evaluated as R_p = 3.8±0.3 and R_n = 3.0±0.3, respectively. These constants are related to the strength of the asymptotic wave function of nucleons in ⁴He and thus to the tail of the nucleon distribution. A comparison of R_p with the empirical proton distribution in ⁴He as deduced from e-⁴He elastic scattering shows excellent agreement. From R_p and R_n the effective ranges of the singlet ³H-p and ³He-n interactions in the ground state of ⁴He are determined to be equal, in accordance with charge symmetry, and to have a value of r_eff = 1.072±0.006 fm.     

Generalized Pearson distributions for charged particles interacting with an electric and/or a magnetic field

The linear Boltzmann equation for elastic and/or inelastic scattering is applied to derive the distribution function of a spatially homogeneous system of charged particles spreading in a host medium of two-level atoms and subjected to external electric and/or magnetic fields. We construct a Fokker-Planck approximation to the kinetic equations and derive the most general class of distributions for the given problem by discussing in detail some physically meaningful cases. The equivalence with the transport theory of electrons in a phonon background is also discussed.