Primary Energy Region Research Articles

The primary energy spectrum with the Linsley method correcting heavy primary effects in the LAAS experiments

The compact EAS Extensive Air Shower (EAS) array (200 m2 ) and the Linsley method have been used with the aim to observe the primary energy spectrum. The spectral indexes αproton and αiron are obtained as − 2.46 ± 0.17 and − 3.08 ± 0.24, respectively, in the primary energy region of 1016 eV − 1018.5 eV in the single observation of the compact EAS array. Additionally, αproton and αiron are obtained as − 3.12 ± 0.13 and − 3.52 ± 0.17, respectively, in the same primary energy region in the observation by restricting the zenith angle of EAS events.

Measurement of the Cosmic Ray spectra by the ARGO-YBJ experiment

Exploiting the features and location at high altitude (the Cosmic Ray Observatory of Yangbajing in Tibet, China, at about 4,300 m a.s.l.) of the ARGO-YBJ detector, the study of several aspects concerning cosmic ray physics in the primary energy region 1012–1016 eV has been performed. Here, the preliminary results of the measurement of all-particle and light-component (i.e. protons and helium nuclei) energy spectra between few tens TeV and ∼5 PeV will be reported, as obtained from the data of RPC (Resistive Plate Chamber) analog charge readout. The study of such energy region is particularly important to better understand the so called knee of the energy spectrum and its origin, as well as for a powerful cross-check among very different experimental techniques, like balloon/space-borne spectrometers and surface air shower detectors. It also allows to test the hadronic interaction models currently used for investigating particle and cosmic ray physics up the highest energies. Finally, the precise measurements of the cosmic ray energy spectrum and composition make possible a more reliable estimation of the atmospheric neutrino flux, which is crucial for any extra-terrestrial neutrino search.

Measurement of the cosmic ray all-particle and light-component energy spectra with the ARGO-YBJ experiment

The ARGO-YBJ detector, located at high altitude in the Cosmic Ray Observatory of Yangbajing in Tibet (4300 m asl, about 600 g/cm2 of atmospheric depth) provides the opportunity for the study, with unprecedented resolution, of cosmic ray physics in the primary energy region between 1012 and 1016 eV. Preliminary results of the measurements of the all-particle and light-component (i.e. protons and helium) energy spectra between approximately 5 TeV and 5 PeV are reported and discussed.

Measurement of the cosmic ray all-particle and light-component energy spectra with the ARGO-YBJ experiment

The ARGO-YBJ detector, located at high altitude in the Cosmic Ray Observatory of YangBaJing in Tibet (4300 m asl, about 600 g/cm2 of atmospheric depth) provides the opportunity for the study, with unprecedented resolution, of cosmic ray physics in the primary energy region between 1012 and 1016 eV. Preliminary results of the measurements of the all-particle and light-component (i.e. protons and helium) energy spectra between approximately 5 TeV and 5 PeV are reported and discussed.

Is it possible to determine the chemical composition of cosmic rays in the “LORD” lunar experiment?

The results of the simulation of cascade radio emission from ultrahigh-energy cosmic rays in the LORD lunar experiment using circularly polarized antennas are presented. It is shown that based on the characteristics of radio emission caused by cascades from protons and iron nuclei in lunar regolith and escaped into vacuum it is impossible to distinguish these cascades in the primary energy region above 1020 eV.

The History of BATSE

The BATSE experiment on the Compton Gamma-ray Observatory was the first large detector system designed for the study of gamma-ray bursts. The eight large-area detectors allowed full-sky coverage and were optimized to operate in the primary energy region of emission of most GRBs. BATSE provided detailed observations of the temporal and spectral characteristics of several thousand GRBs, and it was the first experiment to provide rapid notifications of the coarse location of many them. It also provided strong evidence for the cosmological distances to GRBs through the observation of the sky distribution and intensity distribution of numerous GRBs. The large number of GRBs observed with the high- sensitivity BATSE detectors continues to provide a database of GRB spectral and temporal properties in the primary energy range of GRB emission that will likely not be exceeded for at least another decade. The origin and development of the BATSE experiment, some highlights from the mission and its continuing legacy are described in this paper.

High statistics measurement of the underground muon pair separation at Gran Sasso

We present a measurement of the underground decoherence function using multi-muon events observed in the MACRO detector at Gran Sasso at an average depth of 3800 hg/cm2. Muon pair separations up to 70 m have been measured, corresponding to parent mesons with P⊥<~1–2 GeV/c. Improved selection criteria are used to reduce detector effects mainly in the low distance separation region of muon pairs. Special care is given to a new unfolding procedure designed to minimize systematic errors in the numerical algorithm. The accuracy of the measurement is such that the possible contribution of rare processes, such as μ±+N→μ±+N+μ++μ−, can be experimentally studied. The measured decoherence function is compared with the predictions of the hadronic interaction model of the HEMAS Monte Carlo code. Good agreement is obtained. We interpret this agreement to indicate that no anomalous P⊥ components in soft hadron-nucleus and nucleus-nucleus collisions are required by the MACRO experimental data. Preliminary comparisons with other Monte Carlo codes point out that the uncertainties associated with the hadronic interaction model may be as large as 20%, depending on the energy. MACRO data can be used as a benchmark for future work on the discrimination of shower models in the primary energy region around and below the knee of the spectrum.Received 19 January 1999DOI:https://doi.org/10.1103/PhysRevD.60.032001©1999 American Physical Society

The charge ratio of cosmic ray muons

Prompted by recent accurate measurements of the charge ratio of atmospheric muons, the flux and energy spectra of positive and negative muons have been studied on the basis of Monte-Carlo simulations of the EAS development (CORSIKA), using the GHEISHA and VENUS model as generators. The results have been analysed and compared with data under the aspect of their sensitivity to details of the hadronic interaction, in particular in the 3 GeV/n – 20 TeV/n primary energy region. The muon charge ratio proves to be a sensitive test quantity for the production model and propagation and it exhibits peculiar features at low energies (

Determination of the angle of incidence in a Cameca IMS‐4f SIMS instrument

AbstractAn improved model for the calculation of the angle of incidence of primary ions is presented for describing secondary ion mass spectrometry (SIMS) measurements in the low primary energy region (&lt;7.5 keV) of a Cameca IMS‐4f with positive primary ions and a positive secondary detection mode. The model explains some of the inconsistencies observed between experiment and the approximative model used so far. Our improvement takes into account the effect of the deflection plates for beam positioning, which leads to a change in the angle of the primary ion with respect to the optical axis of the primary column. A comparison with experimental results is accomplished, showing the improvement of the new model. This new model also explains the slope of the crater bottom in the x‐direction at low primary ion energies, owing to a different sputter yield from one side to the other of the crater bottom.

Vibrational electron energy loss spectroscopy of the Si(111)(7×7)–H2O(D2O) system

High-resolution electron energy loss spectroscopy (EELS) has been applied to the study of the Si(111)(7×7)–H2O(D2O) system. At 300 K, H2O(D2O) is partially dissociated on the Si(111) surface to form the SiOH(SiOD) and SiH(SiD) species. Angle and primary-electron-energy dependences of the vibrational loss intensities were measured. Relative contributions to the vibrational excitations of the dipole, impact, and resonance mechanisms were estimated. The O–H(O–D) stretching and Si–O–H (Si–O–D) bending vibrations are partly excited by the resonance mechanism in the primary energy region of Ep ≂2–7 eV. EELS spectra of the Si(111) surface exposed to H2O(D2O) at 300 K and of the same surface heated to ∼700–900 K are presented, and surface reaction mechanisms are discussed.

Evaluations of mass of target isobar and four-momentum transfer in cosmic-ray jets

Direct quantitative evaluations of four-momentum transfer, inelasticity and mass of target isobars in cosmic-ray jets have been carried out with the information of target particles. Average value of fourmomentum transfer to target particles ΔN is found to be ∼ 0.7 GeV for the jets with /γc>=18.5. Occurence of jets with small four-momentum transfer (ΔN⩽1 GeV) is found to be ∼ 0.5 for the primary energy region of (1011÷1013) eV and ∼ 0.6 for that of (1013÷1014) eV. Slight tendency to correlation between ΔN andns is seen although ΔN is evaluated independently ofns. Target isobars so far investigated are dominated by the resonance of isotopic spinI=3/2. When one takes into account the formation of target isobars, the value of four-momentum transfer ΔN increases slightly.

The secondary electron emission from metals in the low primary energy region

This paper describes a new method and apparatus for measuring and analysing the secondary electron emission from non-gaseous materials. It has been devised especially for dealing with secondary emissions caused by primary electrons of very small energy. The essential features include a beam of primary electrons defined and controlled by an electrostatic electron lens system, which directs it towards the centre of a sphere A of the material investigated. A is surrounded by a concentric conducting sphere which collects the secondary electrons emitted from the surface of A . With the arrangement as set up it is possible to measure the contact potential difference between essential elements of the apparatus during the course of the experiments, without moving them or doing anything which would change the nature or composition of their surfaces. The method is applied to the case of pure gets-free copper with primary electrons having energies down to the lowest practicable with a tungsten thermionic source (about 0.35 eV at 2000° K). The distribution of energy is analysed both for the primary and the secondary electrons. It is found to be practically the same for both groups for all energies below a few volts. From this we deduce (1) that for these low-energy electrons the secondary electrons are just reflected electrons, and (2) that the coefficient of reflexion r varies very little with the energy of the electrons. Numerous direct determinations of r have been made. It is shown that no manipulation with fields can ever reduce the mean energy of electrons from a thermionic source below 2 kT , where T is the temperature of the source and k is Boltzmann’s constant. Many determinations of r have been made from a few volts down to 2 kT , and the average value of r is about 0.24. No variation of r has been established with certainty, but there are indications that it drops a little from the value at 2 kT to a minimum at about 2 kT + 0.5 eV, then increases slightly.