First results on the interactions of relativistic $^9$C nuclei in nuclear track emulsion
D. O. Krivenkov, D. A. Artemenkov, V. Bradnova, M. Haiduc, S. P. Kharlamov, V. N. Kondratieva, A. I. Malakhov, A. A. Moiseenko, G. I. Orlova, N. G. Peresadko, N… 展开作者
D. O. Krivenkov, D. A. Artemenkov, V. Bradnova, M. Haiduc, S. P. Kharlamov, V. N. Kondratieva, A. I. Malakhov, A. A. Moiseenko, G. I. Orlova, N. G. Peresadko, N. G. Polukhina, P. A. Rukoyatkin, V. V. Rusakova, V. R. Sarkisyan, R. Stanoeva, T. V. Shchedrina, S. Vokál, P. I. Zarubin, I. G. Zarubina
备注：
7 pages, 6 figures, 2 tables, Presented at Advanced Studies Institute (ASI), SPIN-Praha-2008, Prague, July 20 - July 26, 2008. To be published in in The European Physical Journal Special Topics (EJP ST) Series
\indent描述了核径迹乳剂在能量为1.2 A GeV的$^9$ C核富集的次级束流中曝光的首次结果。呈现的统计量对应于大多数外周$^9$ C相互作用。第一次解离$^9$ C $\to3^3$ He不伴随着目标片段和介子被确定。\par
英文摘要：
\indent First results of the exposure of nuclear track emulsions in a secondary beam enriched by $^9$C nuclei at energy of 1.2 A GeV are described. The presented statistics corresponds to the most peripheral $^9$C interactions. For the first time a dissociation $^9$C $\to3^3$He not accompanied by target fragments and mesons is identified.\par
It is shown that in central collisions of $^{197}$Au nuclei with heavy emulsion nuclei at 11.6 $A$GeV/c two-particles pseudorapidity correlations for produced particles in terms of correlation functions demonstate predominantly long-range behaviour in contrast to nucleon-nucleon interactions. The experimental data are compared with calculations based on the FRITIOF-M model and the model of independent emission of particles.
Nuclear track emulsion is exposed to a beam of radioactive $^8$He nuclei with an energy of 60 MeV and enrichment of about 80% at the ACCULINNA separator. Measurements of 278 decays of the $^8$He nuclei stopped in the emulsion allow the potential of the $α$ spectrometry to be estimated and the thermal drift of $^8$He atoms in matter to be observed for the first time.
Exposures of test samples of nuclear track emulsion were analyzed. Angular and energy correlations of products originating from the thermal-neutron-induced reaction n$_{th} + ^{10}$B $\rightarrow ^{7}$Li $+ (γ) + α$ were studied in nuclear tack emulsions enriched in boron. Nuclear track emulsions were also irradiated with $^{86}$Kr$^{+17}$ and $^{132}$Xe$^{+26}$ of energy about 1.2 MeV per nucleon. Measurements of ranges of heavy ions in nuclear track emulsions made it possible to determine their energies on the basis of the SRIM model. The formation of high-multiplicity nuclear stars was obse…
Forward-backward multiplicity correlations of target fragments in nucleus-emulsion collisions at a few hundred MeV/nucleon
本文研究了150 A MeV He-乳胶、290 A MeV C-乳胶、400 A MeV C-乳胶、400 A MeV Ne-乳胶和500 A MeV Fe-乳胶相互作用中靶蒸发碎片（黑径迹粒子）和靶反冲质子（灰径迹粒子）的前向-后向多重数和关联。结果表明，灰、黑和重电离径迹粒子的前向和后向平均多重数随靶尺寸的增大而增大。前向黑径迹粒子、后向黑径迹粒子和后向灰径迹粒子的平均多重数与粒子大小和能量无关，但前向灰径迹粒子的平均多重数随粒子大小和能量的增加而增加。后向灰径迹粒子多重数分布服从指数衰减规律，衰减常数随目标尺寸的增大而减小。前后向多重数关联遵循线性规律，与弹丸尺寸和能量无关，在某些重目标数据集中观察到饱和效应。
Status and prospects of nuclear clustering studies by dissociation of relativistic nuclei in nuclear track emulsion are presented. The unstable $^{8}$Be and $^{9}$B nuclei are identified in dissociation of the isotopes $^{9}$Be, $^{10}$B, $^{10}$C and $^{11}$C, and the Hoyle state in the cases $^{12}$C and $^{16}$O. On this ground searching for the Hoyle state and more complex $α$-particle states in the dissociation of the heavier nuclei is suggested. A detailed study of a low-density baryonic matter arising in dissociation of the heaviest nuclei is forthcoming long-term problem. An analysis o…
Fragmentation of relativistic nuclei in peripheral interactions in nuclear track emulsion
核径迹乳胶技术被用来探索轻相对论核的碎裂，直到最外围的相互作用-核“白”星。一个完整的模式thererelativistic解离的$^8$ B核与目标片段伴奏。利用显著性统计方法研究了相对论离解$^{9}$ Be $\to2α$，并建立了$^{8}$ Be从0 $^+$和2 $^+$态衰变的相对贡献.显示了相对论碎裂$^{14}$ NPDMATHABMS 3 He +H和$^{22}$ Ne $\to$ 5 He的靶碎片谱。在所有这些情况下，重核上的电磁离解相对于靶质子上的碎裂的主导作用被证明。可以认为，核径迹乳胶中相对论性核的周边离解是研究与核天体物理相关的能标中最轻核和核子组成的多体系统的独特工具。
The fragment separator ACCULINNA in the G. N. Flerov Laboratory of Nuclear Reactions of JINR was used to expose a nuclear track emulsion to a beam of radioactive $^{8}$He nuclei of energy of 60 MeV and enrichment of about 80%. Measurements of decays of $^{8}$He nuclei stopped in the emulsion allow one to evaluate possibilities of $α$-spectrometry and to observe a thermal drift of $^{8}$He atoms in matter. Knowledge of the energy and emission angles of $α$-particles allows one to derive the energy distribution of $α$-decays Q$_{2α}$. The presence of a "tail" of large values Q$_{2α}$ is establis…
The charge topology in the fragmentation of $^{10}$C nuclei in a track nuclear emulsion at an energy of 1.2 GeV per nucleon is studied. In the coherent dissociation of $^{10}$C nuclei, about 82% of events are associated with the channel $^{10}$C $\rightarrow$ 2$α+$ 2\emph{p}. The angular distributions and correlations of product fragments are presented for this channel. It is found that among $^{10}$C $\rightarrow$ 2$α+$ 2\emph{p} events, about 30% are associated with the process in which dissociation through the ground state of the unstable $^9$Be$_{g.s.}$ nucleus is followed by $^8$Be$_{g.s.…
Production of ensembles of $α$-particle triples associated with the Hoyle state (the second excited state of the ${}^{12}$C nucleus) in peripheral dissociation of relativistic ${}^{12}$C nuclei is studied. Stacks of nuclear track emulsion pellicles exposed to ${}^{12}$C with an energy from hundreds MeV to a few GeV per nucleon serve as the material for studies. The Hoyle state decays are reconstructed via measurement of emission angles of $α$ particles with the precision sufficient for identification of the unstable ${}^{8}$Be nucleus. The estimate of the contribution of Hoyle's state to the $…
This article is dedicated to the results of early measuring fragmentation of relativistic $^{16}$O, $^{22}$Ne, $^{28}$Si, and $^{197}$Au nuclei in a nuclear track emulsion. It has been found that there is a contribution of the unstable $^8$Be nucleus decays to $α$-particle multiplicities. These renewed measurements of nuclear track emulsion exposed to $^{84}$Kr nuclei at the energy of 950 MeV per nucleon have been analyzed and given below.
A role of the unstable nuclei ${}^{6}$Be, ${}^{8}$Be and ${}^{9}$B in the dissociation of relativistic nuclei ${}^{7,9}$Be, ${}^{10}$B and ${}^{10,11}$C is under study on the basis of nuclear track emulsion exposed to secondary beams of the JINR Nuclotron. Contribution of the configuration ${}^{6}$Be + $\mit{n}$ to the ${}^{7}$Be nucleus structure is 8 $\pm$ 1% which is near the value for the configuration ${}^{6}$Li + $\mit{p}$. Distributions over the opening angle of $α$-particle pairs indicate to a simultaneous presence of virtual ${}^{8}$Be$_{g.s.}$ and ${}^{8}$Be$_{2^+}$ states in the gro…
In this work we present some results of the interaction of high energy muons with emulsion nuclei. The interaction results in emission of a number of fragments as a consequence of electromagnetic dissociation of the excited target nuclei. This excitation is attributed to absorption of photons by the target nuclei due to the intense electric field of the very fast incident muon particles. The interactions take place at impact parameters that allows ultra-peripheral collisions to take place, leading to giant resonances and hence multi-fragmentation of emulsion targets. Charge identification, ran…
A study of multiplicity distribution of singly charged, doubly charged, multi charged projectile fragments and shower particles have been carried out for the peripheral collisions in 16O-emulsion,22Ne-emulsion and 28Si-emulsion interactions at an incident momentum of (4.1-4.5) AGeV/c. Events having no target fragments have been designated as peripheral collision events. Percentage of peripheral events has been found to increase with the increase of projectile mass. Dispersion of the multiplicity distribution and its dependence on projectile mass for projectile fragments and shower particles ha…
This work presents the basic characteristics of singly, doubly and heavily charged projectile fragments (PFs) emitted in inelastic interactions of 32S ions with photo-emulsion nuclei at Dubna energy (3.7A GeV). Our experimental data are compared with the corresponding data for other projectiles at the same incident energy. The study of mean multiplicities of different charged PFs against the projectile mass shows a power-law relationship. The multiplicity distributions of singly and doubly charged PFs have been fitted well with a Gaussian distribution function. The yields of PFs broken up from…
Clustering in light nuclei in fragmentation above 1 A GeV
用相对论不变量方法分析了3.3 A GeV $^{22}$ Ne在核径迹乳胶中的碎裂.用2.1 A GeV的$^{14}$ N和1.2 A GeV的$^{9}$ Be核对乳胶进行辐照，获得了少体解离的新结果。可以断言，使用不变的方法是一种有效的手段，获得的行为的系统，涉及几个He核在一个相对能量接近1兆电子伏每核子的结论。首次观测到1.2 A GeV的$^{8}$ B和$^{9}$ C核在乳胶中碎裂。所提出的结果允许一个证明核天体物理学的少体方面的发展。
The total nuclear reaction cross-section is calculated considering with and without medium effect by employing Coulomb Modified Glauber Model (CMGM) for interactions of projectiles 56^Fe_26, 84^Kr_36, 132^Xe_54, 197^Au_79 and 238^U_92 with nuclear emulsion detector (NED) nuclei at around 1 GeV per nucleon incident kinetic energy. These calculated reaction cross-sections are correlated with the different target groups of the NED nuclei. The average value of various parameters are also calculated and compared with the corresponding experimental results. The number of shower particles emitted in …
Application of the nuclear track emulsion technique (NTE) in radioactivity and nuclear fission studies is discussed. It is suggested to use a HSP-1000 automated microscope for searching for a collinear cluster tri-partition of heavy nuclei implanted in NTE. Calibrations of $α$-particles and ion ranges in a novel NTE are carried out. Surface exposures of NTE samples to a ${}^{252}$Cf source started. Planar events containing fragments and long-range $α$-particles as well as fragment triples only are studied. NTE samples are calibrated by ions Kr and Xe of energy of 1.2 and 3 A MeV.
Neutron imaging is a non-destructive inspection technique with a wide range of applications. One of the important aspects concerning neutron imaging is achieving micrometer-scale spatial resolution. Developing a neutron detector with a high resolution is a challenging task. Neutron detectors, based on fine-grained nuclear emulsion, may be suitable for high resolution neutron imaging applications. High track density is a necessary requirement to improve the quality of neutron imaging. However, the available track analysis methods are difficult to apply under high track density conditions. Simul…
The charge topology of coherent-dissociation events is presented for $^{11}$C and $^{12}$N nuclei of energy 1.2~\textit{A}~GeV per nucleon bombarding nuclear track emulsions. This topology is compared with respective data for $^{7}$Be, $^{8,10}$B, $^{9,10}$C and $^{14}$N nuclei.
We developed an efficient classifier that sorts alpha-decay events from various vertex-like objects in nuclear emulsion using a convolutional neural network (CNN). Alpha-decay events in the emulsion are standard calibration sources for the relation between the track length and kinetic energy in each emulsion sheet. We trained the CNN using 15,885 images of vertex-like objects including 906 alpha-decay events and tested it using a dataset of 46,948 images including 255 alpha-decay events. By tuning the hyperparameters of the CNN, the trained models achieved an Average Precision Score of 0.740 +…
A new type of cold/ultracold neutron detector that can realize a spatial resolution of less than 100 nm was developed using nuclear emulsion. The detector consists of a fine-grained nuclear emulsion coating and a 50-nm thick $^{10}$B$_4$C layer for the neutron conversion. The detector was exposed to cold and ultracold neutrons (UCNs) at the J-PARC. Detection efficiencies were measured as (0.16$\pm$0.02)% and (12$\pm$2)% for cold and ultracold neutrons consistently with the $^{10}$B content in the converter. Positions of individual neutrons can be determined by observing secondary particle trac…
Five $Ξ^- p\to ΛΛ$ two-body capture events in $^{12}$C and $^{14}$N emulsion nuclei, in which a pair of single-$Λ$ hypernuclei is formed and identified by their weak decay, have been observed in $(K^-,K^+)$ emulsion exposures at KEK and J-PARC. Applying a $Ξ^-$-nucleus optical potential methodology to study atomic and nuclear transitions, we confirm that these capture events occur from Coulomb assisted $1p_{Ξ^-}$ nuclear states. Long-range $ΞN$ shell-model correlations are found essential to achieve consistency between the $^{12}$C and $^{14}$N events. The resulting $Ξ$-nuclear interaction is …
The dissociation of relativistic $^{12}$N nuclei having a momentum of 2 GeV/c per nucleon and undergoing the most peripheral interactions in a track emulsion is studied. The picture of charged topology of product ensembles of relativistic fragments and special features of their angular distributions are presented.
All five KEK and J-PARC two-body $Ξ^-$+$^A$Z $\to$ $^{A'}_Λ$Z'+$^{A''}_Λ$Z'' capture events in light emulsion nuclei, including KISO and IBUKI in $^{14}$N, are consistent with Coulomb-assisted $1p_{Ξ^-}$ nuclear states. The underlying $Ξ$-nuclear potential is strongly attractive, with nuclear-matter depth $V_Ξ$ larger than 20 MeV. The recent $^{14}$N capture events KINKA and IRRAWADDY assigned by J-PARC E07 to $1s_{Ξ^-}$ nuclear states, and implying considerably shallower $V_Ξ$, have also another interpretation as $1p_{Ξ^0}$ nuclear states.
Correlations of $α$-particles are studied on statistics of 400 events of splitting $^{12}$C $\rightarrow$ 3$α$ in nuclear track emulsion exposed to $14.1 MeV$ neutrons. The ranges and emission angles of the $α$-particles are measured. Distributions over energy of $α$-particle pairs and triples are obtained.
In this paper, the correlation between the formation of the unstable $^{8}$Be nucleus and accompanying $α$ particles in the fragmentation of relativistic $^{16}$O, $^{22}$Ne, $^{28}$Si, and $^{197}$Au nuclei in a nuclear track emulsion is investigated. The $^{8}$Be decays are identified in a wide energy range by invariant masses calculated from 2$α$-pair opening angles. The adopted approximations are verified by data on fragmentation of $^{16}$O nuclei in a hydrogen bubble chamber in a magnetic field. An increase in the $^{8}$Be contribution to the dissociation with the growth of $α$-particle …
In the events of peripheral dissociation of relativistic nuclei in the nuclear track emulsion, it is possible to study the emerging ensembles of He and H nuclei, including those from decays of unstable $^{8}$Be and $^{9}$B nuclei, as well as the Hoyle state. These extremely short-lived states are identified by invariant masses calculated from the angles in 2$α$-pairs, 2$αp$- and 3$α$-triplets in the approximation of conservation of momentum per nucleon of the primary nucleus. In the same approach, it is possible to search for more complex states. This paper explores the correlation between the…
The invariant mass method is used to identify the $^8$Be and $^9$B nuclei and Hoyle state formed in dissociation of relativistic nuclei in a nuclear track emulsion. It is shown that to identify these extremely short-lived states in the case of the isotopes $^9$Be, $^{10}$B, $^{10}$C, $^{11}$C, $^{12}$C, and $^{16}$O, it is sufficient to determine the invariant mass as a function of the angles in pairs and triples of He and H fragments in the approximation of the conservation of momentum per nucleon of the parent nucleus. According to the criteria established in this way, the contribution of th…
In the context of the search for triples of relativistic $α$-particles in the Hoyle state, the analysis of available data on the dissociation of the nuclei ${}^{12}$C, ${}^{16}$O and ${}^{22}$Ne in the nuclear emulsion was carried out. The Hoyle state is identified by the invariant mass calculated from pair angles of expansion in $α$-triples in the approximation of the conservation of the momentum per nucleon of the parent nucleus. The contribution of the Hoyle state to the dissociation of ${}^{12}$C $\to$ 3$α$ is 11\%. In the case of the coherent dissociation of ${}^{16}$O $\to$ 4$α$ it reach…
Multi-pronged events from Coulomb fission of nuclei at very low energies
用$^{252}$ Cf裂变源在聚对苯二甲酸乙二酯（$_{10}$ H $_8$ O $_4$）$_n$固体核径迹探测器上记录了多分叉径迹。在化学腐蚀后，在光学显微镜下观察到两叉到六叉的径迹以及单径迹。我们进行了系统的研究，以了解叉的起源。径迹探测器涂有金属（Cu、Ag和Pb）并暴露于$^{252}$ Cf源。在化学蚀刻后，在每个板中观察到两叉至四叉的轨迹。我们相信，在1 MeV/A量级的极低能量下，库仑裂变是这种多管齐下的轨道起源的唯一合理解释。
