Search

A reanalysis of experimental data from the RUssia-Nippon JOint Balloon (RUNJOB) emulsion experiment on the basis of a new method aimed at searches for primary galactic particles in events identified as those of nucleon-nucleus interaction confirmed the original result that consisted in the absence of a large number (about 50%) of tracks of incident particles. A comparative analysis of such events where there is a detected primary track and where there is no primary track was performed in terms of the energy, angular distribution, and depth of penetration into x-ray emulsion chambers (XREC). The hypothesis that a neutral component is present in cosmic rays at the XREC exposure level is discussed.

A rare event observed in a nuclear emulsion is reported. The RUNJOB Russian-Japanese balloon experiment detected the interaction of a high-energy neutral particle in a nuclear emulsion plate of an X-ray emulsion chamber exposed in 1999.

Experimental and methodological errors in the coordinate prediction for primary cosmic ray nucleons and nuclei in nuclear emulsions using a new method for searching and tracing particle tracks in emulsion films of X-ray emulsion chambers (XRECs) exposed in the stratosphere in the Russia–Nippon Joint Balloon (RUNJOB) experiment are considered in detail. The dependence of errors on the relation between angular characteristics of the sought particle and auxiliary multiply charged nuclei is analyzed. Angular selection criteria for auxiliary nuclei, at which the methodological error of the particle track coordinate prediction decreases, are found.

An continuing search for primary particles is performed using a new means of finding and tracking particles in nuclear emulsions. Particle interactions registered in stratospheric X-ray emulsion chambers (XECs) are attributed to nucleon–nuclei interactions recorded in the Russian–Japanese RUNJOB experiment. According to the data from processing the interactions between galactic particles and matter in XECs RUNJOB-3B, 6A, and RUNJOB-11A, 11B with energy thresholds ΣE γ ≥ 3 and ΣE γ ≥ 5 TeV, respectively, around 50% of all proton tracks went unidentified, which coincides with the initial results from the RUNJOB experiment.

The objective of this paper is not a detailed review or an analysis of the studies in the field of high-energy physics initiated by the discovery of Vavilov–Cherenkov radiation, occurred more than 80 years ago at the Lebedev Physical Institute, and awarded Nobel Prizes. The paper is written to emphasize the historical significance of the discovery of the effect and its key role in further studies in high-energy physics, commended by the high award of the Nobel committee. In 1958, 24 years after the first publication about the new phenomenon, i.e., emission of electrons moving in matter with the superlight speed, discovered by P.A. Cherenkov under the supervision by S.I. Vavilov, the Nobel Prize was awarded to a group of scientists of the Lebedev Physical Institute, P.A. Cherenkov, I.M. Frank, and I.E. Tamm “for the discovery and explanation of the Cherenkov effect”. Since then, practical application of Vavilov–Cherenkov radiation is widely spread.

Primary single-charged particles were identified in ∼50% of the proton events in the Russian-Japanese RUNJOB balloon experiment. In reprocessing the experimental data obtained via long-term exposure of the RUNJOB-3B, 6A, 11A, and 11B emulsion chambers (ECs) using a new approach to searching for primary cosmic-ray particles in groups of proton events with primary particle energy E0 > 20 TeV and zenith angle tan(θ) ≤ 5, ∼50% of the primary single-charged particles went unidentified, as was the case earlier. In this work, we describe the new approach to searching for and tracking particles in ECs and present the parameters of the processed events (energy, zenith angle, depth of particle penetration into an EC up to interaction).

In the RUNJOB Russian-Japanese balloon experiment, tracks of primary singly charged particles are detected in approximately half the events related to the proton ones. During repeated processing of the experimental data obtained when exposing RUNJOB-3B, 6A, 11A, and 11B X-ray emulsion chambers (XRECs) using the new method for searching primary cosmic particles, approximately 50% of tracks of primary singly charged particles as before were not detected in the group of events related to the proton ones with primary particle energiesE0 > 20 TeV and zenith angle tan θ ≤ 5. In this paper,we present a new method for searching and tracing particles in the XREC; characteristics of processed events (the energy, zenith angle, and particle penetration depth in the XREC before the interaction) are given.

In the RUNJOB experiment, a long-term exposure of x-ray emulsion chambers in the stratosphere from 1995 to 1999 with the aim of studying the composition and spectra of primary cosmic particles in the energy range 10–1000 TeV per nucleon revealed about 50% proton tracks. The remaining events of the proton group did not feature any candidate for a track of a singly charged particle within the search region determined from measurements of the coordinates of background nuclei going close to the sought track. Methodological factors that could explain this experimental observation are considered. A possible physical reason associated with the presence of a neutral component in the flux of primary protons in the energy region above 10 TeV is also analyzed.

シャワー拡散層付エマルションチェンバーによるエネルギー決定法について報告する． この方法は，1995年の日ロ共同気球実験(RUNJOB-program, RUssia-Nippon JOint Balloon-program) で観測されたPeV陽子のエネルギー推定方法を基に開発され，1997年のRUNJOB実験より導入した．シャワー拡散層はカロリメーター層の下部に設置され，カロリメーター層で発達した電磁カスケードシャワーはシャワー拡散層で幾何学的に広がり，電子数密度が減少する．普通，電磁カスケードシャワーによるエネルギー決定の場合，シャワー最大発達点を捉えていないとそのエネルギーは信頼できない．しかし，本論文で報告する方法により，シャワー極大を捉えていない場合でもエネルギー決定が可能となった．約４ｃｍの厚さのシャワー拡散層があれば陽子の場合，６c.u.の鉛厚で数１０TeVまで，９c.u.あれば１００TeV近くまでシャワーエネルギーをσ～０．２以内の精度で決定できる．又，鉄核の場合，６c.u.の鉛厚で１００TeVまでのシャワーエネルギーをやはりσ～０．２以内の精度で決定できる．したがって，これまでシャワー極大を捉えていないためデータとして採用できないような高エネルギーシャワーについてもエネルギー決定が行え，特に高エネルギー領域の統計量を増やす事ができる．本論文では，主にシャワー拡散層付エマルションチェンバー内でのカスケードシャワーシミュレーション方法およびエネルギー決定精度について議論する．また実際にRUNJOB実験データに対して適用した例についても報告する．, We report a new energy determination method using the emulsion calorimeter with diffuser module. The idea of diffuser method is based on the energy estimation for a PeV proton observed by the first RUNJOB(RUssia-Nippon JOint Balloon-program) experiment in 1995 and we have used a new type of emulsion chamber with diffuser module since 1997. The diffuser module was set below calorimeter, and the electromagnetic cascade shower develops in the calorimeter, and spreads geometcally in the diffuser. In general, it is very hard to determine the energy unless we detect the shower maximum, but it might be possible to determine the shower energy with help of the diffuser module. We find the energy resolution is better than σ～0.2 for proton with several tens TeV and for iron with 100TeV if the path length of calorimeter and the diffuser are 6c.u. and 4cm respectively. With the thickness of calorimeter of 9c.u. with 4cm diffuser, we can estimate the energy up to nearly 100TeV for proton with the resolution of better than σ～0.2. In this report, we disscus the energy resolution in the present method based on the simulation calculation of cascade shower in the calorimeter with diffuser module. We show several events observed by RUNJOB experiment in 1997 and alloy the present method for the energy determination., 資料番号: SA0200107000

We report experimental results obtained by the emulsion chambers on board of the long duration balloon. We have been carrying out the trans-Siberian-continental balloon flight since 1995, and the results from 1995 to 1996 experiments are presented here. Total exposure of these two years amounts to 231.5 m 2 h at the average altitude of ∼32 km. The energy range covers 10–500 TeV for proton-primary, 3–70 TeV/n for helium-primary, and 1–5 TeV/n for Fe-group ( Z =26–28), though statistics of heavy components is not yet enough. Our preliminary data show that the spectra of the proton and the helium have nearly the same power indices ∼2.80, while those of heavier ones become gradually harder as the mass gets heavier, for instance the index is ∼2.70 for CNO-group and ∼2.55 for Fe-group. It is remarkable that a very high energy proton with multi-PeV is detected in 1995 experiment, and the estimated flux of this event coincides with a simple extrapolation from the energy spectrum with the power index 2.8 observed in the range 10–500 TeV. It indicates that there is no spectral break at around 100 TeV, in contrast to the maximum energy predicted by the current shock-wave acceleration model. This evidence requires some modification on the acceleration and/or propagation mechanism. Also we present all-particle spectrum and the average primary mass in the energy range 20–1000 TeV/particle. Our preliminary data show no drastic change in mass composition over the wide energy range, at least up to 1 PeV/particle, though the statistics is not yet enough to confirm it concretely. The flight performance and the procedure of the analysis, particularly the energy determination methods and the detection efficiency calculation are also given.

We report experimental results obtained by using a wide-gap type emulsion chamber flown in the first Japanese-Russo joint balloon project, called RUNJOB ( RU ssia- N ippon JO int B alloon-program). Two balloons were launched from Kamchatka in July 1995, and both were recovered successfully near the Volga River. The exposure time was 130 hours for the first flight and 168 hours for the second. The mean ceiling altitude, in both flights, was 32 km corresponding to 10 g/cm 2 . Total area of the emulsion chamber was 0.8 m 2 , and the thickness 0.385 and 2.28 collision m.f.p.'s for vertically incident proton- and iron-primaries, respectively. We detected 381 showers using Fuji-#200-type X-ray film; of these 174 showers were due to atmospheric secondary γ-rays, and the rest 207 came from nuclear components. The energy range covers 20∼200 TeV for proton-primary, 3∼30 TeV/nucleon for helium-primary, and 0.7∼5 TeV/nucleon for iron-primary. We give the energy spectra for various elements (proton, helium, …, iron) as well as the all-particle spectrum and the average mass of the cosmic-ray primaries.

The latest results of studies of the gamma-ray spectra recorded together with charged particles in the Russian-Nippon Joint Balloon (RUNJOB) experiment are presented. A comparison of the experimental spectra with the results of the calculations based on assumptions of different intensities of the gamma-ray spec- tra demonstrates that the previously published intensities of primary cosmic rays measured in the RUNJOB experiments are underestimated.

The primary proton tracks are identified in about half of events referred to proton ones in the Russian-Japanese balloon-born emulsion chamber RUNJOB experiment. Reprocessing of experimental data obtained in long-term exposure of RUNJOB-3B, 6A, 11A, 11B emulsion chambers (EC) with new method for searching of the primary cosmic particles leads to confirm that as well as earlier single charged primary tracks are not found in about half of events referred to the proton ones with energy E0 > 20 TeV and zenith angle tg(θ) ≤ 5. In this paper the new method for searching and tracing of the primary cosmic particles in EC's and characteristics of studied events (energy, angle, pass length of the primary particles until their interaction in EC) are presented.