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Gas Cells for 3He Hyperpolarized via Spin-exchange Optical Pumping
김우영,S. S. Stepanyan,A. Kim,J. A. TAN,S. Woo 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.2
We present a device for the production of hyperpolarized 3He, which is widely used in spinrelated nuclear physics research. Spin-exchange optical pumping (SEOP) is employed to polarize 3He enclosed in a circular borosilicate glass cell suitable not only for the production of polarized gas but also for its storage. The portable glass cell can, thus, be transported to any other research facility. The glass cell can be refilled several times. Special attention is given to the preparation and the filling of the cell to minimize the impurities on its walls and in the gas. We employ glass tubes with shorter lengths and larger diameters in the gas-filling system to achieve the improvement in the air flow necessary to obtain purer polarized 3He samples. The cell is prepared, and after it has been filled with rubidium (Rb) and 3He-N2 mixture, it is sealed under high vacuum conditions. The cell containing the mixture is exposed to circularly-polarized laser light with a wavelength of 795 nm at temperatures of 180 − 220 C for SEOP. The polarization of 3He is measured via nuclear magnetic resonance (NMR). We obtained 40% polarized 3He in less than 15 hours and 50% in about 25 hours. The longitudinal relaxation time T1 of the polarized 3He we measured was about 58 hours.
Roman Hovsepyan,Nina Stepanyan-Gandilyan,Hamlet Melkumyan,Lili Harutyunyan 한국식품연구원 2016 Journal of Ethnic Foods Vol.3 No.1
Background: The traditional food of the Yezidis and Kurds of Armenia has some particularities and differences compared with the traditional cuisine of Armenians. Methods: Ethnobotanical data collected during fieldworks in 2013e2015 in Armenia via interviews, direct observations and sampling of used plants for identification of species. Results: Traditional dishes of Yezidis and Kurds are simple. They are mostly made from or contain as a main component lamb and milk products (sometimes beef and chicken, but never pork). The main vegetal components of their traditional food are represented by cultivated cereals, grains, and herbs of wild plants. Edible plants gathered from the wild are used primarily for nutritional purposes, for flavoring prepared meals and milk products, and for tea. Discussion: We correlate these distinctions with the transhumant pastoral lifestyle of the Yezidi and Kurdish people.
Polarized 129Xe Production by Using the Spin Exchange Optical Pumping Method
CHEBOTARYOVSERGEY,김우영,MILMANEVGENIY,S. Stepanyan 한국물리학회 2013 새물리 Vol.63 No.2
Polarized 129Xe can be used as a gaseous contrast agent for medical resonance imaging (MRI) and which provides better resolution to evaluate lung and other body tissues in vivo. We are developing a setup for 129Xe gas polarization based on the optical-pumping spin-exchange method. The system can produce high quantities of highly-polarized 129Xe atoms and consist of Helmholtz solenoid coils,a high-power diode laser, the optical elements for forming the circularly-polarized laser beam, and “Apollo” nuclear magnetic resonance (NMR) system for measuring the 129Xe polarization level and a vacuum handling system. In this article, we will discuss the current status of our setup.
Microwave System for a Solid Proton Target Polarized via Optical Pumping
Joshua Artem TAN,Yonggeun SEON,김우영,Vladimir KAVTANYUK,Samuel S. STEPANYAN,Young Kwan KWON 한국물리학회 2016 새물리 Vol.66 No.2
We present the microwave system of the polarizer set-up for the solid proton target used in investigating the spin-orbit properties of unstable nuclei. Such a target is a paramagnetic radical-doped crystal having a high hydrogen density. Through the absorbtion of laser light of an appropriate frequency, the dopant’s electrons become polarized, and through the application of the microwave system’s oscillating magnetic field at the particular frequency and amplitude that satisfies the Hartmann-Hahn condition for resonance, the electrons polarization is transferred to the protons. Thus, the microwave system plays the most important role in solid proton target polarization. The microwave signal is initially generated in the network analyzer, enhanced via the amplifier, monitored with a power meter, and converted to an oscillating magnetic field in the loop-gap resonator. We observed the resonance of our loop gap-generator around 4.5 GHz with a scattering parameter of $\sim$-45 dB.
Near-threshold photoproduction of φ mesons from deuterium
CLAS Collaboration,Qian, X.,Chen, W.,Gao, H.,Hicks, K.,Kramer, K.,Laget, J.M.,Mibe, T.,Qiang, Y.,Stepanyan, S.,Tedeschi, D.J.,Xu, W.,Adhikari, K.P.,Amaryan, M.,Anghinolfi, M.,Ball, J.,Battaglieri, M. North-Holland Pub. Co 2011 Physics letters: B Vol.696 No.4
We report the first, kinematically-complete measurement of the differential cross section of φ-meson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, K<SUP>+</SUP> and K<SUP>-</SUP> near the theoretical production threshold of 1.57 GeV. The extracted differential cross sections dσdt for the initial photon energy range of 1.65-1.75 GeV are consistent with predictions based on a quasifree mechanism. Our finding is different from recent LEPS results on φ-meson photoproduction from deuterium in a similar incident photon energy range, but in a different momentum transfer region.
CLAS Collaboration,Pereira, S.A.,Mirazita, M.,Rossi, P.,De Sanctis, E.,Niculescu, G.,Niculescu, I.,Stepanyan, S.,Adhikari, K.P.,Aghasyan, M.,Anghinolfi, M.,Baghdasaryan, H.,Ball, J.,Battaglieri, M.,Be North-Holland Pub. Co 2010 Physics letters: B Vol.688 No.4
<P>Differential cross sections of the reaction gamma d -> K+Sigma(-)(p) have been measured with the CLAS detector at Jefferson Lab using incident photons with energies between 1.1 and 3.6 GeV. This is the first complete set of strangeness photoproduction data on the neutron covering a broad angular range. At energies close to threshold and up to E-gamma similar to 1.8 GeV. the shape of the angular distribution is suggestive of the presence of s-channel production mechanisms. For E-gamma > 1.8 GeV, a clear forward peak appears and becomes more prominent as the photon energy increases, suggesting contributions from t-channel production mechanisms. These data can be used to constrain future analysis of this reaction. (c) 2010 Elsevier B.V. All rights reserved.</P>
The extraction of φ–N total cross section from d(γ,p<sup>K+</sup><sup>K−</sup>)n
Qian, X.,Chen, W.,Gao, H.,Hicks, K.,Kramer, K.,Laget, J.M.,Mibe, T.,Stepanyan, S.,Tedeschi, D.J.,Xu, W.,Adhikari, K.P.,Amaryan, M.,Anghinolfi, M.,Baghdasaryan, H.,Ball, J.,Battaglieri, M.,Batourine, V Elsevier 2009 Physics letters: B Vol.680 No.5
<P><B>Abstract</B></P><P>We report on the first measurement of the differential cross section of <I>φ</I>-meson photoproduction for the d(γ,p<SUP>K+</SUP><SUP>K−</SUP>)n exclusive reaction channel. The experiment was performed using a tagged-photon beam and the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. A combined analysis using data from the d(γ,p<SUP>K+</SUP><SUP>K−</SUP>)n channel and those from a previous publication on coherent <I>φ</I> production on the deuteron has been carried out to extract the φ−N total cross section, <SUB>σφN</SUB>. The extracted φ−N total cross section favors a value above 20 mb. This value is larger than the value extracted using vector-meson dominance models for <I>φ</I> photoproduction on the proton.</P>