Different scanning schemes based on the RF cavities for non-relativistic electron beam have been ... more Different scanning schemes based on the RF cavities for non-relativistic electron beam have been examined. Optimisation criteria for various types of cavities have been developed. A complete picture of the beam scanning at a given point of interest is obtained.
ABSTRACT A Λ hypernuclear spectroscopic experiment, JLab E05-115 was performed at JLab Hall-C in ... more ABSTRACT A Λ hypernuclear spectroscopic experiment, JLab E05-115 was performed at JLab Hall-C in 2009 by the (e, e′K+) reaction. Data of Λ hypernuclei with mass numbers from A = 7 to A = 52 were successfully taken, and the analyses are in progress. A polyethylene (CH2) target was used as a proton target to calibrate energy scales, and to study elementary process of the p(e, e′K+)Λ, Σ0 reaction. A preliminary differential cross section of K+Λ electro-production at low Q2 [~0.01 (GeV/c)2] and at small kaon angles ${({\rm cos} \theta_{\rm K}^{\rm CM} \sim 0.97)}$ is reported in the present article.
The development of the advanced Radio Frequency Timer of electrons is described. It is based on a... more The development of the advanced Radio Frequency Timer of electrons is described. It is based on a helical deflector, which performs circular or elliptical sweeps of keV electrons, by means of 500 MHz radio frequency field. By converting a time distribution of incident electrons to a hit position distribution on a circle or ellipse, this device achieves extremely precise timing. Streak Cameras, based on similar principles, routinely operate in the ps and sub-ps time domain, but have substantial slow readout system. Here, we report a device, where the position sensor, consisting of microchannel plates and a delay-line anode, produces ~ns duration pulses which can be processed by using regular fast electronics. A photon sensor based on this technique, the Radio Frequency Photo-Multiplier Tube (RFPMT), has demonstrated a timing resolution of ~10 ps and a time stability of ~0.5 ps, FWHM. This makes the apparatus highly suited for Time Correlated Single Photon Counting which is widely used in optical microscopy and tomography of biological samples. The first application in lifetime measurements of quantum states of graphene, under construction at the A. I. Alikhanyan National Science Laboratory (AANL), is outlined. This is followed by a description of potential RFPMT applications in time-correlated Diffuse Optical Tomography, time-correlated Stimulated Emission Depletion microscopy, hybrid FRET/STED nanoscopy and Time-of-Flight Positron Emission Tomography.
On the growth of the total cross section for hadronic photoabsorption
The energy dependence of the total cross section for hadronic photoabsorption is discussed in con... more The energy dependence of the total cross section for hadronic photoabsorption is discussed in connection with the hypothesis that the growth of the cross sections has a gluon character.
We present results from a joint theoretical and experimental study of inclusive quasifree electro... more We present results from a joint theoretical and experimental study of inclusive quasifree electrofission of 238 U. The off-shell cross sections for the quasifree reaction stage have been calculated within the plane wave impulse approximation with distortion corrections included in the effective momentum approximation. Proton and neutron single-particle momentum distributions were calculated in the macroscopic-microscopic approach. The fissility for proton and neutron single hole excited states of the residual nuclei 237 Pa and 237,238 U was calculated within the compound nucleus model. Final state interaction corrections to residual nucleus excitation energy were calculated using the imaginary part of the optical potential. The total inclusive electrofission cross section was measured with high absolute precision, and all principal partial contributions are analyzed, in particular, the quasifree one.
Hypernuclei are convenient laboratory to study the baryon-baryon weak interaction and associated ... more Hypernuclei are convenient laboratory to study the baryon-baryon weak interaction and associated effective Hamiltonian. The strangeness changing process, in which a Λ hyperon converts to a neutron with a release up to 176 MeV, provides a clear signal for a conversion of an s-quark to a d-quark. We propose to perform a non-mesonic weak decay study of Be 10 Λ hypernuclei using the (e,e'K +) reaction. These investigations will fully utilize the unique parameters of the CEBAF CW electron beam and RF system and are enabled by (1) the use of new detector for alpha particles based on the recently developed RF timing technique with picosecond resolution and (2) the small angle and large acceptance kaon spectrometer-HKS in Hall C.
A spectroscopy of a 10 Λ Be hypernucleus was carried out at JLab Hall C using the (e, e ′ K +) re... more A spectroscopy of a 10 Λ Be hypernucleus was carried out at JLab Hall C using the (e, e ′ K +) reaction. A new magnetic spectrometer system (SPL+HES+HKS), specifically designed for high resolution hypernuclear spectroscopy, was used to obtain an energy spectrum with a resolution of ∼ 0.78 MeV (FWHM). The well-calibrated spectrometer system of the present experiment using p(e, e ′ K +)Λ,Σ 0 reactions allowed us to determine the energy levels, and the binding energy of the ground state peak (mixture of 1 − and 2 − states) was obtained to be B Λ = 8.55 ± 0.07(stat.) ± 0.11(sys.) MeV. The result indicates that the ground state energy is shallower than that of an emulsion study by about 0.5 MeV which provides valuable experimental information on Charge Symmetry Breaking (CSB) effect in the ΛN interaction.
Proposal for a Photon Detector with Picosecond Time Resolution
NATO Science Series II: Mathematics, Physics and Chemistry
... V. Popov a , L. Tang a , H. Vardanyan b , C.Yan a ... They include vacuum-based devices such ... more ... V. Popov a , L. Tang a , H. Vardanyan b , C.Yan a ... They include vacuum-based devices such as the Multi-anode PMT [17,18], Micro Channel Plates (MCP) [19] as well as an array of Si PIN [20] and Avalanche Photodiodes (APD) [21] or APD working in a Geiger mode (SiPM) [22 ...
Measurement of total hadronic photoabsorption cross section on carbon from 14 to 34 GeV
Physics Letters B, 1975
ABSTRACT The data on total cross section of hadronic photoabsorption in carbon nuclei as obtained... more ABSTRACT The data on total cross section of hadronic photoabsorption in carbon nuclei as obtained by conventional tagged photon method are given for five values of energy in 14-34 GeV interval. A slight drop of cross section curve with the increase in energy is observed, indicating the contribution of varrho'-meson to the total cross section.
An experiment with a newly developed high-resolution kaon spectrometer (HKS) and a scattered elec... more An experiment with a newly developed high-resolution kaon spectrometer (HKS) and a scattered electron spectrometer with a novel configuration was performed in Hall C at Jefferson Lab (JLab). The ground state of a neutron-rich hypernucleus, 7 Λ He, was observed for the first time with the (e, e ′ K +) reaction with an energy resolution of ∼0.6 MeV. This resolution is the best reported to date for hypernuclear reaction spectroscopy. The 7 Λ He binding energy supplies the last missing information of the A = 7, T = 1 hypernuclear iso-triplet, providing a new input for the charge symmetry breaking (CSB) effect of ΛN potential.
Ultrahigh accuracy time synchronization technique based on the Optical Frequency Comb and the GHZ... more Ultrahigh accuracy time synchronization technique based on the Optical Frequency Comb and the GHZ radiofrequency spiral scanning deflector is suggested to install on the Moon during the ARTEMIS mission. The comparison with the parameters of an analogous device operated in the Earth's gravity will enable the testing to high accuracy fundamental physical principles. The installation of retroreflectors on the Moon by Apollo 11 and by subsequent missions and Lunar laser ranging opened entire new paths for research, from testing of fundamental physics, General Relativity, Nordtvedt effect 1 , up to a bunch of issues of the structure and evolution of the Moon. The present proposal aims the operation on the Moon during the ARTEMIS mission of to date the highest accuracy synchronization technique. Present proposal is based on authors' experience on to date the highest accuracy test of light speed invariance (Kennedy-Thorndike test) at the GRAAL experiment at European Synchrotron Radiation Facility (ESRF, Grenoble) [1], General Relativity's Lense-Thirring effect testing via LARES satellite laser ranging measurements [2],[3]. Femtosecond optical frequency combs (OFC) are revolutionizing precision measurements of time and frequency [4]. The simplicity, robustness and improved precision femtosecond lasers have now led to their prominence in the field of optical frequency metrology [5]. In addition, their use is developing significant new time domain applications based on the precise control of the carrier-envelope phase, as involved in the present proposal.
[sub Lambda][sup 10]Be and [sub Lambda][sup 10]B hypernuclei: A clue to some puzzles in nonmesonic weak decay
We demonstrate how the nuclear structure aspects of the problem, an often unwelcome detail of the... more We demonstrate how the nuclear structure aspects of the problem, an often unwelcome detail of the calculations attempting to understand basic two-body interactions, can be used to pick out components of the effective weak Hamiltonian.
Measurement of electrofission cross sections and photofission yields of sup 235 U and sup 238 U in the energy region 1. 33--4. 32 GeV
Soviet Journal of Nuclear Physics, 1989
Measurements of the electrofission cross sections and photofission yields in the nuclei {sup 235}... more Measurements of the electrofission cross sections and photofission yields in the nuclei {sup 235}U and {sup 238}U are reported for electron and bremsstrahlung spectrum energies in the region 1--5 GeV. The data were obtained in experiments with a multiwire low-pressure chamber for detection of fission fragments.
Recently a new photon detector the Radio Frequency Photo Multiplier Tube(RFPMT) was developed at ... more Recently a new photon detector the Radio Frequency Photo Multiplier Tube(RFPMT) was developed at Yerevan Physics Institute. The time resolution and minimal time bin for single photons detected by RFPMT is about a picosecond. The RFPMT can be operated at MHz rates and with a dedicated spiral scanning system operational rates can achive THz over a short interval of about 100 ns, while the longer term averaged rate would be at the GHz level. We propose to establish a new company in Armenia, for commercialization of RFPMTs and eventually to start developing of scientific and medical instruments based on RFPMTs, such as the RF-STED nanoscope; the diffuse optical tomography; the time-of-flight positron emission tomography and etc. for academic, research and clinical applications.
Different scanning schemes based on the RF cavities for non-relativistic electron beam have been ... more Different scanning schemes based on the RF cavities for non-relativistic electron beam have been examined. Optimisation criteria for various types of cavities have been developed. A complete picture of the beam scanning at a given point of interest is obtained.
ABSTRACT A Λ hypernuclear spectroscopic experiment, JLab E05-115 was performed at JLab Hall-C in ... more ABSTRACT A Λ hypernuclear spectroscopic experiment, JLab E05-115 was performed at JLab Hall-C in 2009 by the (e, e′K+) reaction. Data of Λ hypernuclei with mass numbers from A = 7 to A = 52 were successfully taken, and the analyses are in progress. A polyethylene (CH2) target was used as a proton target to calibrate energy scales, and to study elementary process of the p(e, e′K+)Λ, Σ0 reaction. A preliminary differential cross section of K+Λ electro-production at low Q2 [~0.01 (GeV/c)2] and at small kaon angles ${({\rm cos} \theta_{\rm K}^{\rm CM} \sim 0.97)}$ is reported in the present article.
The development of the advanced Radio Frequency Timer of electrons is described. It is based on a... more The development of the advanced Radio Frequency Timer of electrons is described. It is based on a helical deflector, which performs circular or elliptical sweeps of keV electrons, by means of 500 MHz radio frequency field. By converting a time distribution of incident electrons to a hit position distribution on a circle or ellipse, this device achieves extremely precise timing. Streak Cameras, based on similar principles, routinely operate in the ps and sub-ps time domain, but have substantial slow readout system. Here, we report a device, where the position sensor, consisting of microchannel plates and a delay-line anode, produces ~ns duration pulses which can be processed by using regular fast electronics. A photon sensor based on this technique, the Radio Frequency Photo-Multiplier Tube (RFPMT), has demonstrated a timing resolution of ~10 ps and a time stability of ~0.5 ps, FWHM. This makes the apparatus highly suited for Time Correlated Single Photon Counting which is widely used in optical microscopy and tomography of biological samples. The first application in lifetime measurements of quantum states of graphene, under construction at the A. I. Alikhanyan National Science Laboratory (AANL), is outlined. This is followed by a description of potential RFPMT applications in time-correlated Diffuse Optical Tomography, time-correlated Stimulated Emission Depletion microscopy, hybrid FRET/STED nanoscopy and Time-of-Flight Positron Emission Tomography.
On the growth of the total cross section for hadronic photoabsorption
The energy dependence of the total cross section for hadronic photoabsorption is discussed in con... more The energy dependence of the total cross section for hadronic photoabsorption is discussed in connection with the hypothesis that the growth of the cross sections has a gluon character.
We present results from a joint theoretical and experimental study of inclusive quasifree electro... more We present results from a joint theoretical and experimental study of inclusive quasifree electrofission of 238 U. The off-shell cross sections for the quasifree reaction stage have been calculated within the plane wave impulse approximation with distortion corrections included in the effective momentum approximation. Proton and neutron single-particle momentum distributions were calculated in the macroscopic-microscopic approach. The fissility for proton and neutron single hole excited states of the residual nuclei 237 Pa and 237,238 U was calculated within the compound nucleus model. Final state interaction corrections to residual nucleus excitation energy were calculated using the imaginary part of the optical potential. The total inclusive electrofission cross section was measured with high absolute precision, and all principal partial contributions are analyzed, in particular, the quasifree one.
Hypernuclei are convenient laboratory to study the baryon-baryon weak interaction and associated ... more Hypernuclei are convenient laboratory to study the baryon-baryon weak interaction and associated effective Hamiltonian. The strangeness changing process, in which a Λ hyperon converts to a neutron with a release up to 176 MeV, provides a clear signal for a conversion of an s-quark to a d-quark. We propose to perform a non-mesonic weak decay study of Be 10 Λ hypernuclei using the (e,e'K +) reaction. These investigations will fully utilize the unique parameters of the CEBAF CW electron beam and RF system and are enabled by (1) the use of new detector for alpha particles based on the recently developed RF timing technique with picosecond resolution and (2) the small angle and large acceptance kaon spectrometer-HKS in Hall C.
A spectroscopy of a 10 Λ Be hypernucleus was carried out at JLab Hall C using the (e, e ′ K +) re... more A spectroscopy of a 10 Λ Be hypernucleus was carried out at JLab Hall C using the (e, e ′ K +) reaction. A new magnetic spectrometer system (SPL+HES+HKS), specifically designed for high resolution hypernuclear spectroscopy, was used to obtain an energy spectrum with a resolution of ∼ 0.78 MeV (FWHM). The well-calibrated spectrometer system of the present experiment using p(e, e ′ K +)Λ,Σ 0 reactions allowed us to determine the energy levels, and the binding energy of the ground state peak (mixture of 1 − and 2 − states) was obtained to be B Λ = 8.55 ± 0.07(stat.) ± 0.11(sys.) MeV. The result indicates that the ground state energy is shallower than that of an emulsion study by about 0.5 MeV which provides valuable experimental information on Charge Symmetry Breaking (CSB) effect in the ΛN interaction.
Proposal for a Photon Detector with Picosecond Time Resolution
NATO Science Series II: Mathematics, Physics and Chemistry
... V. Popov a , L. Tang a , H. Vardanyan b , C.Yan a ... They include vacuum-based devices such ... more ... V. Popov a , L. Tang a , H. Vardanyan b , C.Yan a ... They include vacuum-based devices such as the Multi-anode PMT [17,18], Micro Channel Plates (MCP) [19] as well as an array of Si PIN [20] and Avalanche Photodiodes (APD) [21] or APD working in a Geiger mode (SiPM) [22 ...
Measurement of total hadronic photoabsorption cross section on carbon from 14 to 34 GeV
Physics Letters B, 1975
ABSTRACT The data on total cross section of hadronic photoabsorption in carbon nuclei as obtained... more ABSTRACT The data on total cross section of hadronic photoabsorption in carbon nuclei as obtained by conventional tagged photon method are given for five values of energy in 14-34 GeV interval. A slight drop of cross section curve with the increase in energy is observed, indicating the contribution of varrho'-meson to the total cross section.
An experiment with a newly developed high-resolution kaon spectrometer (HKS) and a scattered elec... more An experiment with a newly developed high-resolution kaon spectrometer (HKS) and a scattered electron spectrometer with a novel configuration was performed in Hall C at Jefferson Lab (JLab). The ground state of a neutron-rich hypernucleus, 7 Λ He, was observed for the first time with the (e, e ′ K +) reaction with an energy resolution of ∼0.6 MeV. This resolution is the best reported to date for hypernuclear reaction spectroscopy. The 7 Λ He binding energy supplies the last missing information of the A = 7, T = 1 hypernuclear iso-triplet, providing a new input for the charge symmetry breaking (CSB) effect of ΛN potential.
Ultrahigh accuracy time synchronization technique based on the Optical Frequency Comb and the GHZ... more Ultrahigh accuracy time synchronization technique based on the Optical Frequency Comb and the GHZ radiofrequency spiral scanning deflector is suggested to install on the Moon during the ARTEMIS mission. The comparison with the parameters of an analogous device operated in the Earth's gravity will enable the testing to high accuracy fundamental physical principles. The installation of retroreflectors on the Moon by Apollo 11 and by subsequent missions and Lunar laser ranging opened entire new paths for research, from testing of fundamental physics, General Relativity, Nordtvedt effect 1 , up to a bunch of issues of the structure and evolution of the Moon. The present proposal aims the operation on the Moon during the ARTEMIS mission of to date the highest accuracy synchronization technique. Present proposal is based on authors' experience on to date the highest accuracy test of light speed invariance (Kennedy-Thorndike test) at the GRAAL experiment at European Synchrotron Radiation Facility (ESRF, Grenoble) [1], General Relativity's Lense-Thirring effect testing via LARES satellite laser ranging measurements [2],[3]. Femtosecond optical frequency combs (OFC) are revolutionizing precision measurements of time and frequency [4]. The simplicity, robustness and improved precision femtosecond lasers have now led to their prominence in the field of optical frequency metrology [5]. In addition, their use is developing significant new time domain applications based on the precise control of the carrier-envelope phase, as involved in the present proposal.
[sub Lambda][sup 10]Be and [sub Lambda][sup 10]B hypernuclei: A clue to some puzzles in nonmesonic weak decay
We demonstrate how the nuclear structure aspects of the problem, an often unwelcome detail of the... more We demonstrate how the nuclear structure aspects of the problem, an often unwelcome detail of the calculations attempting to understand basic two-body interactions, can be used to pick out components of the effective weak Hamiltonian.
Measurement of electrofission cross sections and photofission yields of sup 235 U and sup 238 U in the energy region 1. 33--4. 32 GeV
Soviet Journal of Nuclear Physics, 1989
Measurements of the electrofission cross sections and photofission yields in the nuclei {sup 235}... more Measurements of the electrofission cross sections and photofission yields in the nuclei {sup 235}U and {sup 238}U are reported for electron and bremsstrahlung spectrum energies in the region 1--5 GeV. The data were obtained in experiments with a multiwire low-pressure chamber for detection of fission fragments.
Recently a new photon detector the Radio Frequency Photo Multiplier Tube(RFPMT) was developed at ... more Recently a new photon detector the Radio Frequency Photo Multiplier Tube(RFPMT) was developed at Yerevan Physics Institute. The time resolution and minimal time bin for single photons detected by RFPMT is about a picosecond. The RFPMT can be operated at MHz rates and with a dedicated spiral scanning system operational rates can achive THz over a short interval of about 100 ns, while the longer term averaged rate would be at the GHz level. We propose to establish a new company in Armenia, for commercialization of RFPMTs and eventually to start developing of scientific and medical instruments based on RFPMTs, such as the RF-STED nanoscope; the diffuse optical tomography; the time-of-flight positron emission tomography and etc. for academic, research and clinical applications.
Uploads
Papers by Amur Margaryan