Lightning environment in the vicinity of the CN tower during major storms

Based on the North American Lightning Detection Network data and the return-stroke currents recorded at the CN Tower, the lightning environment within 100 km from the CN Tower is thoroughly investigated, especially while the tower was struck with major storms in 2011 and 2005. On Aug 24, 2011, video records showed that the tower was struck with 52 flashes within about 84 minutes, pointing out to the most intense storm that has ever been observed at the tower. During this most intense storm, the tower’s current measurement system recorded 32 flashes, containing 161 return strokes, resulting in an average flash multiplicity of 5, which is 80% higher than the average multiplicity of flashes occurring in the vicinity of the tower. Since the tower is repeatedly hit by lightning and its flashes produce markedly higher number of strokes, then it definitely poses an electromagnetic interference risk to nearby sensitive installations, including those in downtown Toronto.

Lightning environment in the vicinity of the CN tower during major storms

Based on the North American Lightning Detection Network data and the return-stroke currents recorded at the CN Tower, the lightning environment within 100 km from the CN Tower is thoroughly investigated, especially while the tower was struck with major storms in 2011 and 2005. On Aug 24, 2011, video records showed that the tower was struck with 52 flashes within about 84 minutes, pointing out to the most intense storm that has ever been observed at the tower. During this most intense storm, the tower’s current measurement system recorded 32 flashes, containing 161 return strokes, resulting in an average flash multiplicity of 5, which is 80% higher than the average multiplicity of flashes occurring in the vicinity of the tower. Since the tower is repeatedly hit by lightning and its flashes produce markedly higher number of strokes, then it definitely poses an electromagnetic interference risk to nearby sensitive installations, including those in downtown Toronto.

Systematic study of the de-excitation of neutron-rich nuclei produced in different fission reactions

In this paper we present results from two recent studies, both related to the emission of prompt fission γ rays. Firstly, we have analyzed data from the reaction 235U(n, f) induced by fast neutrons of average energy E̅n = 1.7 MeV. The deduced spectral characteristics are an average multiplicity M̅γ = 7.11 ± 0.44 γ rays per fission and an average total γ-ray energy release in fission E̅γ,tot = 5.51 ± 0.46 MeV, corresponding to an average γ-ray energy ɛ̅γ = 0.77 ± 0.08 MeV. Secondly, we have addressed – and answered – the question how those characteristics in general depend on the width of the chosen prompt time window and the timing resolution, determined by the employed detectors and electronics. The conclusion is that once this is known, it is possible to compare results from different experiments in a more meaningful way.

Study of relativistic charged particles production in 84Kr36 emulsion interactions ∼1GeV per nucleon with wounded nucleon model

The experimental results on the multiplicity and probability distribution of the emitted charged pions [Formula: see text] in the interactions of [Formula: see text]Kr[Formula: see text] projectile at around 1[Formula: see text]GeV per nucleon with nuclear emulsion targets are reported. In this work, we have employed a wounded nucleon model (WNM) to calculate the total number of wounded nucleons [Formula: see text] and the total number of interactions [Formula: see text]. The dependence of average multiplicities of produced relativistic charged particles on the calculated wounded nucleons and total interactions are investigated. The obtained results revealed that the average multiplicity of [Formula: see text] is dependent on the projectile and target mass number. The calculated values of the total number of wounded nucleons and the total numbers of interactions show a strong dependence on the mass of the colliding nuclei. The emission rate of the mean multiplicity of [Formula: see text] and [Formula: see text] linearly increases with increasing the total number of wounded nucleons and interactions.

Projectile fragmentation study in peripheral collision for the interaction of the 84Kr with nuclear emulsion at relativistic energy

This paper focuses on the emission characteristics of single-, double- and multi-charged projectile fragments in the interaction of [Formula: see text]Kr with nuclear emulsion in peripheral collision at relativistic energy. We have also studied the variation of the average multiplicity of multi-charged projectile fragments with respect to the mass of the projectile beam, which reveals that the average multiplicity of multiple charge fragments increases with an increase in the mass of projectile beam. The results are consistent with other experimental observations.

New Instruments for Nuclear Astrophysics

A major task in experimental nuclear astrophysics is the measurement of cross sections of capture reactions. In the last years, the astrophysics group of NCSR “Demokritos” developed and used a method for conducting this kind of research using a 4π NaI γ-detector. Of great importance in this method is the determination of the efficiency of the detector, which depends on the average multiplicity of the γ-cascade de-exciting the entry state of the produced nucleus. Two new experimental setups have been studied and are in course of installation at the Tandem Laboratory of the Institute of Nuclear and Particle Physics of NCSR “Demokritos”, that will provide the possibility for conducting this kind of experiments inhouse. The first one is a new 14x14 inches NaI detector and the second is the BGO Ball of the GASP setup. These detector setups as well as their potential experimental use will be described in detail.

Observation of Gaussian Pseudorapidity Distributions for Produced Particles in Proton-Nucleus Collisions at Tevatron Energies

The statistical event-by-event analysis of inelastic interactions of protons in emulsion at 800 GeV reveals the existence of group of events with Gaussian pseudorapidity distributions for produced particles, as suggested by hydrodynamic-tube model. Events belong to very central collisions of protons with heavy emulsion nuclei with probability of realization of less than 1% and with multiplicity of shower particles exceeding (2-3 times) the average multiplicity in proton-nucleus collisions in emulsion. Bjorken’s energy density for these events reaches 2.0 GeV per fm3. The data are interpreted as a result of the QCD phase transition in proton-tube collisions at Tevatron energies.

Centrality dependence of total disintegration of target nuclei in high energy nucleus–nucleus interactions

A study of centrality dependence of target fragmentation and multiparticle production has been carried out in 16O–AgBr, 22Ne–AgBr, and 28Si–AgBr interactions at 4.1–4.5 AGeV/c for the total disintegrated (TD) events. Average multiplicity of black particles increases linearly with decreasing centrality while average multiplicity of grey and shower particles decreases with decreasing centrality for the TD events. The decrease of average multiplicity of grey particles is linear; on the other hand, in the case of shower particles, the increase is nonlinear. With the increase of the mass of the projectile beam, the average multiplicity of black particles decreases and the average multiplicity of grey particles increases for the TD events. This observation has been explained on the basis of the fireball model; however, in the case of shower particles, average multiplicity increases with increase of projectile mass.