Evidence of Anomalous Behavior of Relativistic Alpha Particles Emitted inC12-Emulsion Interaction at 4.5 GeV/cper Nucleon

Abstract

This paper presents evidence of the anomalous interaction mean free path of the relativistic alpha particles emitted from the interaction of 12 C with emulsion nuclei at 4.5 GeV/c per nucleon. The tracks were followed systematically through the stack. The detailed measurements show clearly that the interaction mean free path is anomalously shorter for fewer centimeters after their emission. The results have been compared with other results obtained from both accelerator and cosmic-ray data.PACS numbers: 25.70.Np Evidence for anomalously short interaction mean free paths of projectile fragments of different charges from high-energy ion collisions has been observed in cosmic-ray studies. 1 " 8 This has further been supplemented by the observation in emulsion experiments 9 " 12 of similar effects of projectile fragments from 2.1-GeV/nucleon O 16 beam and 1.88-GeV/c 56 Fe and 40 Ar beams from accelerators.To arrive at any confident conclusion about "anomalons" (projectile fragments with anomalous interaction mean free paths), it is absolutely essential to have good statistics of individual charges which is very difficult for higher Z values. Since it has been known for a long time that the fragmentation of heavy primaries into alpha particles is very common, one can confirm the anomalous behavior by taking large statistics of a (i.e., Z = 2) particles as projectile fragments emitted from emulsion nuclei exposed at accelerators to high-energy heavy-ion beams. Jain et al. u have found that in the case of two heavy-ion beams of 40 Ar and 56 Fe at 2A GeV the interaction mean free paths for alpha particles are the same at all distances from their production points. We present in this paper an investigation on anomalous reaction mean free paths of alpha-particle projectile fragments emitted from 12 Cemulsion interaction at 4.5 GeV/ c per nucleon.Our results based on detailed observation can be summarized as follows: (1) The interaction mean free path is anomalously short for a few centimeters after emission.(2) The interaction mean free paths measured at different path lengths from the points of emission are different. (3) The interaction mean free path shows a definite increase in value with increasing path-length interval. (4) The interaction mean free path of particles emitted from primary interaction stars of n h ^ 8 is shorter than for those emitted from stars of n h > 8 in the path-length interval 0-4 cm.The observations were made in a stack of ten plates of NIKFI-BR-2 nuclear emulsion, of pellicle dimensions 10x20 cm 2 x600 /mm with printed grid. The plates were tangentially irradiated with the 4.5A-GQV/C 12 C beam at the Joint Institute for Nuclear Research, Dubna, U.S.S.R. A total of 1200 relativistic alpha particles emitted from the primary interaction within a small forward cone were followed, using Leitz Ortholux microscopes, by the along-the-track method. Identification of a (i.e., Z = 2) particles was carried out by the gap-density method and by 8-ray count for the identification of charge. All electron track...

Does the phenomenon of anomalons really exist?

“…7). It is not clear why the experiments of [25] and [68] give so "strange" from the statistical point of view results (see outliers in Fig. 5).…”

“…After Freidlander's work many experimental results have been published. Some of them show the positive anomalon effect [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]68] but others show no one [28-39, 64, 67, 69, 71, 72, 76]. There exist a lot of theoretical attempts to understand the phenomenon [40-57, 61-63, 70, 75] and experiments verifying them [58][59][60].…”

Mean free paths and interaction cross-section of α-projectile fragments produced in oxygen-emulsion interaction at 60 GeV/n

“…From elementary considerations, it is expected that the probability of interaction per unit distance is constant. Many experimenters [6,7] using several techniques, have repeated observations contrary to the expected constant m.f.p.'s. This is an anomalous behaviour.…”

Interaction mean free paths of He fragments from 3.7A GeV 16O–emulsion collision

“…On the MFPs of helium PFs in nuclear emulsion, four experiments (Ghosh et al, 1985;Ganssauge et al, 1985;El-Nadi et al, 1984;Zhang et al, 2001) saw positive evidences for a reduced MFP, while the others contradicted them (Singh et al, 1988(Singh et al, , 1990Sengupta et al, 1989;Khan et al, 1989;Jain et al, 1985;Ismail et al, 1984;Bhanja et al, 1985;El-Nadi et al, 1993). To explain the possible existence of anomalons, various theoretical models have been proposed, which include the color polarization of quark states (Romo and Watson, 1979), quasi-molecular nuclear states (Bayman et al, 1982), and the relativistic mean-field theory (Rufa et al, 1987(Rufa et al, , 1990Schaffner et al, 1992;Abou-El-Naga, 1990), etc.…”