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The DsTau(NA65) experiment at CERN was proposed to measure an inclusive differential cross-section of D s production with decay to tau lepton and tau neutrino in p – A interactions. The DsTau detector is based on the nuclear emulsion technique, which provides excellent spatial resolution for detecting short-lived particles like charmed hadrons. This paper presents the first results of the analysis of the pilot-run (2018 run) data and reports the accuracy of the proton interaction vertex reconstruction. High precision in vertex reconstruction enables detailed measurement of proton interactions, even in environments with high track density. The measured data has been compared with several Monte Carlo event generators in terms of multiplicity and angular distribution of charged particles. The multiplicity distribution obtained in p–W interactions is tested for KNO-G scaling and is found to be nearly consistent. The interaction length of protons in tungsten is measured to be 93.7 ± 2.6 mm . The results presented in this study can be used to validate event generators of p – A interactions.

Status and prospects of nuclear clustering studies by dissociation of relativistic nuclei in nuclear track emulsion are presented. The unstable 8Be and 9B nuclei are identified in dissociation of the isotopes 9Be, 10B, 10C and nC, and the Hoyle state in the cases 12C and 16O. 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 of nuclear fragmentation induced by relativistic muons is proposed to examine the mechanism dissociation.

Exposures of test samples of nuclear track emulsion were analyzed. The formation of high-multiplicity nuclear stars was observed upon irradiating nuclear track emulsions with ultrarelativistic muons. Kinematical features studied in this exposure of nuclear track emulsions for events of the muon-induced splitting of carbon nuclei to three α-particles are indicative of the nuclear-diffraction interaction mechanism.

Contribution of the unstable nuclei 7Be, 8Be and ®B into coherent dissociation events (\"white\" stars) of relativistic nuclei 7,9Be, 10B and 10,11C is under study on the basis of a nuclear track emulsion exposed to beams of the JINR Nuclotron. Distributions over the opening angle of α-pairs indicate to a simultaneous presence of virtual 8Beg.s. and 8Be2+ states in the ground states of the 9Be and 10C nuclei. The core 9B is manifested in the 10C nucleus with a probability of (30 ± 4)%, Selection of the 10C \"white\" stars accompanied by 8Beg.s. (9B) leads to the appearance in the excitation energy distribution of 2α2p \"quartets\" of the distinct peak with a maximum at 4.1 ± 0.3 MeV. 8Beg.s. decays are presented in 21% 2He + 2H and 19% in the 3He of the all 11C \"white\" stars. 9Bg.s. decays are identified in \"white\" stars 11C → 2He + 2H constituting 14% of the 11C \"white\" stars. The 9B nucleus. is manifested in the \"white\" stars 10B → 2He + 2H with a probability of (9 ± 1)%. For the 10B case yield of 8Beg.s. nuclei with the respect to 9B is about a factor of 3 higher than 9B.

Progress in the study of nuclear clustering in the relativistic 10C and 11C nuclei dissociation in nuclear track emulsion is presented. The contribution of the unbound 8Be and 9B nuclei to their structure is determined on the basis of measurements of the emission angles of relativistic He and H fragments.

Recent findings related with the unstable nuclei 8Be and 9B in the coherent dissociation of relativistic nuclei 10C, 10B and 12C in nuclear track emulsion (“white”stars) are highlighted. Selection of the 10C “white”stars accompanied by 8Be (9B) leads to appearance of the distinct peak with a maximum at 4.1 ± 0.3 MeV in the excitation energy distribution of 2α2p ensembles. The 8Beg.s. nucleus is manifested in the coherent dissociation 10B → 2He + H with a probability of 25 ± 5 % including 13 ± 3 % of 9B decays. A probability ratio of the mirror channels 9B + n and 9Be + p is estimated to be 10 ± 1. Reanalysis of relativistic 12C dissociation in lead enriched emulsion revealed 9 3α-events corresponding to the Hoyle state.

A new design of a detector plane of sub-millimetre thickness for an electromagnetic sampling calorimeter is presented. It is intended to be used in the luminometers LumiCal and BeamCal in future linear e\\[^{+}\\]e\\[^{-}\\] collider experiments. The detector planes were produced utilising novel connectivity scheme technologies. They were installed in a compact prototype of the calorimeter and tested at DESY with an electron beam of energy 1–5 GeV. The performance of a prototype of a compact LumiCal comprising eight detector planes was studied. The effective Molière radius at 5 GeV was determined to be (8.1 ± 0.1 (stat) ± 0.3 (syst)) mm, a value well reproduced by the Monte Carlo (MC) simulation (8.4 ± 0.1) mm. The dependence of the effective Molière radius on the electron energy in the range 1–5 GeV was also studied. Good agreement was obtained between data and MC simulation.

A prototype of a luminometer, designed for a future e+e- collider detector, and consisting at present of a four-plane module, was tested in the CERN PS accelerator T9 beam. The objective of this beam test was to demonstrate a multi-plane tungsten/silicon operation, to study the development of the electromagnetic shower and to compare it with MC simulations. The Molière radius has been determined to be 24.0 ± 0.6 (stat.) ± 1.5 (syst.) mm using a parametrization of the shower shape. Very good agreement was found between data and a detailed Geant4 simulation.

Progress in the study of nuclear clustering in the relativistic 10B and 11C nuclei dissociation in nuclear track emulsion is presented. The contribution of the unbound 8Be and 9B nuclei to their structure is determined on the basis of measurements of the emission angles of relativistic He and H fragments.