A. M. Milov

Experimental investigation of high-energy photon splitting in atomic fields

Data analysis of an experiment in which photon splitting in atomic fields was observed is presented. The experiment was performed at the tagged photon beam of the ROKK-1M facility at the VEPP-4M collider. In the energy region of 120-450 MeV, statistics of 1.6x10(9) photons incident on the BGO target was collected. About 400 candidate photon-splitting events were reconstructed. Within the attained experimental accuracy, the experimental results are consistent with the calculated exact atomic-field cross section. The predictions obtained in the Born approximation differ significantly from the experimental results.

Detector KEDR tagging system for two-photon physics

Abstract A special system to tag scattered electrons from γγ-processes is described. The system is intended for the experiments at the VEPP-4M storage ring. This system has a high detection efficiency and good invariant mass resolution.

The gamma ray energy tagging spectrometer of the ROKK-2 facility at the VEPP-3 storage ring

Abstract A tagging spectrometer for the gamma rays produced by Compton backscattering and bremsstrahlung processes is described. A storage ring bending magnet is used as an electron momentum separator for this spectrometer in the gamma ray energy range from 30 MeV up to 270 MeV. Factors determining the tagging efficiency and the energy resolution are discussed. The energy resolution is measured by the Compton backscattering process. The tagging spectrometer yields a resolution of 4 MeV and a tagging efficiency of 95%.

A Compton source of high energy polarized tagged γ-ray beams. The ROKK-1M facility

The ROKK-1M facility generates high energy polarized γ-ray beams by backscattering of laser light against the high energy electron and positron beams of the VEPP-4M collider. The facility design allows to obtain backscattering of laser light on electron and positron beams separately or simultaneously. Tagging and/or collimation is applied to select a narrow energy band from the γ-quanta spectrum. Operating in a laser polarimeter mode, the ROKK1-M facility is able to measure transverse and longitudinal polarization of the electron and positron beams in the VEPP-4M collider. A description of the facility and achieved γ-ray beam parameters are presented in this paper.

Liquid krypton calorimeter for KEDR detector and last prototype results

Abstract The liquid krypton calorimeter for the KEDR-VEPP-4M experiment is described. The experimental results with a prototype, obtained at the tagged photon beam of VEPP-4M in the photon energy region between 50 and 4500 MeV, are presented. The results on the energy resolution are in a good agreement with the Monte-Carlo expectations and are equal to 6% and 2% at 100 and 1000 MeV respectively. The spatial resolution is about 1–1.5 mm in a wide energy region and agrees with the expected spatial resolution.

ROKK‐1M is the Compton source of the high intensity polarized and tagged gamma beam at the VEPP‐4M collider

The Backward Scattered Compton Quanta light source (ROKK‐1M) developed for the high intensity polarized and tagged gamma beam at the Novosibirsk VEPP‐4M Collider is described. Energy calibration of the electron and positron beams, real‐time measurement of the beam polarization, and the electron‐positron beam emittance at the interaction point are discussed. (AIP)

The test of the LKr calorimeter prototype at the tagged photon beam

Abstract The experiment with the prototype of liquid krypton electromagnetic calorimeter for the KEDR detector is described. The experiment was carried out at the VEPP-4M collider at the tagged photon beam. The tagged photons were obtained in the energy region 50–625 MeV using the ROKK-1M facility. The edges of the bremsstrahlung spectra were used for the energy resolution measurement in the high-energy region up to 4500 MeV. The energy resolution comparable with the resolution of the best crystal calorimeters and the excellent spatial resolution (∼1 mm) have been obtained. The results are in good agreement with the Monte-Carlo simulation.

Fissility of Bi, Pb, Au, Pt, W, Ta, V and Ti nuclei measured with 100 MeV Compton backscattered photons

Photofission cross sections of and nuclei have been measured at an incident photon energy of 100 MeV using monochromatic photons produced by Compton backscattering at the ROKK-1M facility (BINP, Novosibirsk). Detection of fission fragments has been performed by means of Makrofol track-etch detectors in close contact with metallic foils of the target elements. The values of fissility at 100 MeV deduced for the targets under investigation are found to range between and . The present results show consistency with the fissility trends calculated for 69 and 600 MeV monoenergetic photons using a formalism based on the current two-step model for intermediate-energy photofission reactions.

Photofission cross section and fissility of pre-actinide and intermediate-mass nuclei by 120 and 145 MeV Compton backscattered photons

Cross section measurements for photofission induced in , , , and by 120 and 145 MeV quasi-monochromatic photon beams have been performed at the ROKK-1M facility (BINP, Novosibirsk). The fission yields have been obtained using Makrofol sheets as solid-state fission track detectors. Nuclear fissility values have been deduced on the basis of Levingers modified quasi-deuteron model of photonuclear interaction, and compared with available literature data. The trend of fissility in the 60-145 MeV energy range has been analysed for various target nuclei as a function of energy and of the parameter .

Study of the BELLE CsI calorimeter prototype with the BINP tagged photon beam

Abstract The results of the BELLE barrel calorimeter prototype test with the tagged photon beam are presented. The prototype consisted of 36 CsI(Tl) counters with the same readout system as the BELLE calorimeter. The measurements were carried out at the VEPP-4 collider with the tagged photon beam provided by the ROKK-1M facility. The energy resolution for photons was measured in the energy range 40–800 MeV. The results are in good agreement with the Monte-Carlo simulation.