Polarization Modeling and Predictions for DKIST Part 2: Application of the Berreman Calculus to Spectral Polarization Fringes of Beamsplitters and Crystal Retarders

We outline polarization fringe predictions derived from a new application of the Berreman calculus for the Daniel K. Inouye Solar Telescope (DKIST) retarder optics. The DKIST retarder baseline design used 6 crystals, single-layer anti-reflection coatings, thick cover windows and oil between all optical interfaces. This new tool estimates polarization fringes and optic Mueller matrices as functions of all optical design choices. The amplitude and period of polarized fringes under design changes, manufacturing errors, tolerances and several physical factors can now be estimated. This tool compares well with observations of fringes for data collected with the SPINOR spectropolarimeter at the Dunn Solar Telescope using bi-crystalline achromatic retarders as well as laboratory tests. With this new tool, we show impacts of design decisions on polarization fringes as impacted by anti-reflection coatings, oil refractive indices, cover window presence and part thicknesses. This tool helped DKIST decide to remove retarder cover windows and also recommends reconsideration of coating strategies for DKIST. We anticipate this tool to be essential in designing future retarders for mitigation of polarization and intensity fringe errors in other high spectral resolution astronomical systems.Comment: Accepted for publication in JATI

Electron and positron scattering from 1,1-C₂H₂F₂

1,1-difluoroethylene (1,1-C₂H₂F₂) molecules have been studied for the first time experimentally and theoretically by electron and positron impact. 0.4-1000 eV electron and 0.2-1000 eV positron impact total cross sections (TCSs) were measured using a retarding potential time-of-flight apparatus. In order to probe the resonances observed in the electron TCSs, a crossed-beam method was used to investigate vibrational excitation cross sections over the energy range of 1.3-49 eV and scattering angles 90 degrees and 120 degrees for the two loss energies 0.115 and 0.381 eV corresponding to the dominant C-H (ν₂ and ν₉) stretching and the combined C-F (ν₃) stretching and CH₂ (ν₁₁) rocking vibrations, respectively. Electron impact elastic integral cross sections are also reported for calculations carried out using the Schwinger multichannel method with pseudopotentials for the energy range from 0.5 to 50 eV in the static-exchange approximation and from 0.5 to 20 eV in the static-exchange plus polarization approximation. Resonance peaks observed centered at about 2.3, 6.5, and 16 eV in the TCSs have been shown to be mainly due to the vibrational and elastic channels, and assigned to the B₂, B₁, and A₁ symmetries, respectively. The pi* resonance peak at 1.8 eV in C₂H₄ is observed shifted to 2.3 eV in 1,1-C₂H₂F₂ and to 2.5 eV in C₂F₄; a phenomenon attributed to the decreasing C=C bond length from C₂H₄ to C₂F₄. For positron impact a conspicuous peak is observed below the positronium formation threshold at about 1 eV, and other less pronounced ones centered at about 5 and 20 eV.The work was supported in part by a Grant-in-Aid, the Ministry of Education, Science, Technology, Sport and Culture, Japan, the Japan Society for the Promotion of Science JSPS, and the Japan Atomic Energy Research Institute JAERI. One of the authors C.M. is also grateful to the JSPS for financial support under Grant No. P04064. Another author H.T. acknowledges Dr. T. Ozeki of the JAERI for his encouragement and support during this work. This work was also done under the International Atomic Energy Agency IAEA project for three of the authors C.M., M.H., and H.T.. Two of the authors M.H.F.B. and M.A.P.L. acknowledge support from the Brazilian agency Conselho Nacional de Desenvolvimento Científico e Tecnológico CNPq. MHFB also acknowledges support from the Paraná state agency Fundação Araucária and from FINEP ( under Project No. CT-Infra 1)

Electron And Positron Scattering From 1,1- C2 H2 F2

1,1-difluoroethylene (1,1- C2 H2 F2) molecules have been studied for the first time experimentally and theoretically by electron and positron impact. 0.4-1000 eV electron and 0.2-1000 eV positron impact total cross sections (TCSs) were measured using a retarding potential time-of-flight apparatus. In order to probe the resonances observed in the electron TCSs, a crossed-beam method was used to investigate vibrational excitation cross sections over the energy range of 1.3-49 eV and scattering angles 90° and 120° for the two loss energies 0.115 and 0.381 eV corresponding to the dominant C-H (2 and 9) stretching and the combined C-F (3) stretching and C H2 (11) rocking vibrations, respectively. Electron impact elastic integral cross sections are also reported for calculations carried out using the Schwinger multichannel method with pseudopotentials for the energy range from 0.5 to 50 eV in the static-exchange approximation and from 0.5 to 20 eV in the static-exchange plus polarization approximation. Resonance peaks observed centered at about 2.3, 6.5, and 16 eV in the TCSs have been shown to be mainly due to the vibrational and elastic channels, and assigned to the B2, B1, and A1 symmetries, respectively. The π* resonance peak at 1.8 eV in C2 H4 is observed shifted to 2.3 eV in 1,1- C2 H2 F2 and to 2.5 eV in C2 F4; a phenomenon attributed to the decreasing CC bond length from C2 H4 to C2 F4. For positron impact a conspicuous peak is observed below the positronium formation threshold at about 1 eV, and other less pronounced ones centered at about 5 and 20 eV. © 2007 American Institute of Physics.12616(1997) Kyoto Protocol to the United Nations Framework Convention on Climate Change, , http://www.cnn.com/SPECIALS/1997/global.warming/stories/treaty, DecemberMitsui, Y., Ohira, Y., Yonemura, T., Takaichi, T., Sekiya, A., Beppu, T., (2004) J. Electrochem. Soc., 151, p. 297Panajotovic, R., Kitajima, M., Tanaka, H., Jelisavic, M., Lower, J., Campbell, L., Brunger, M.J., Buckman, S.J., (2003) J. Phys. B, 36, p. 1615Szmytkowski, C., Kwitnewski, S., Ptasinska-Denga, E., (2003) Phys. Rev. A, 68, p. 032715Brescansin, L.M., MacHado, L.E., Lee, M.-T., (1998) Phys. Rev. A, 57, p. 3504Winstead, C., McKoy, V., (2002) J. Chem. Phys., 116, p. 1380. , 0021-9606 10.1063/1.1429649Winstead, C., McKoy, V., Bettega, M.H.F., (2005) Phys. Rev. A, 72, p. 042721Coggiola, M.J., Flicker, W.M., Mosher, O.A., Kuppermann, A., (1976) J. Chem. Phys., 65, p. 2655Edgell, W.F., Byrd, W.E., (1949) J. Chem. Phys., 17, p. 740Smith, D.C., Nielsen, J.R., Classen, H.H., (1950) J. Chem. Phys., 16, p. 326Joyner, P., Glockler, G., (1952) J. Chem. Phys., 20, p. 302Roberts, A., Edgell, W.F., (1949) J. Chem. Phys., 17, p. 742. , 0021-9606Roberts, A., Edgell, W.F., (1949) Phys. Rev., 76, p. 178Allan, M., Craig, N.C., McCarty, L.V., (2002) J. Phys. B, 35, p. 523Wahl, R.L., (2002) Principles and Practice of Positron Emission Tomography, , Lippincott, New York/ Williams and Wilkins, BaltimoreSchultz, P.J., Lynn, K.G., (1988) Rev. Mod. Phys., 60, p. 701Mitroy, J., Bromley, M.W.J., Ryzhikh, G.G., (2002) J. Phys. B, 35, p. 81Sueoka, O., Mori, S., Hamada, A., (1994) J. Phys. B, 27, p. 1452Kimura, M., Makochekanwa, C., Sueoka, O., (2004) J. Phys. B, 37, p. 1461Hoffman, K.R., Dababneh, M.S., Hsieh, Y.F., Kauppila, W.E., Pol, V., Smart, J.H., Stein, T.S., (1982) Phys. Rev. A, 25, p. 1393Sueoka, O., Mori, S., (1986) J. Phys. B, 19, p. 4035Sueoka, O., Makochekanwa, C., Kawate, H., (2002) Nucl. Instrum. Methods Phys. Res. B, 192, p. 206Tanaka, H., Ishikawa, T., Masai, T., Sagara, T., Boesten, L., Takekawa, M., Itikawa, Y., Kimura, M., (1998) Phys. Rev. A, 57, p. 1798Srivastava, S.K., Chutjian, A., Trajmar, S., (1975) J. Chem. Phys., 63, p. 2659Takatsuka, K., McKoy, V., (1981) Phys. Rev. A, 24, p. 2473. , 1050-2947 10.1103/PhysRevA.24.2473Takatsuka, K., McKoy, V., (1984) Phys. Rev. A, 30, p. 1734Bettega, M.H.F., Ferreira, L.G., Lima, M.A.P., (1993) Phys. Rev. A, 47, p. 1111Bettega, M.H.F., Natalense, A.P.P., Lima, M.A.P., Ferreira, L.G., (2003) J. Phys. B, 36, p. 1263Lopes, A.R., Bettega, M.H.F., (2003) Phys. Rev. A, 67, p. 032711Varellado, T.M.N., Bettega, M.H.F., Lima, M.A.P., Ferreira, L.G., (1999) J. Chem. Phys., 111, p. 6396Rescigno, T.N., McCurdy, C.W., Schneider, B.I., (1989) Appl. Phys. Lett., 63, p. 248Winstead, C., McKoy, V., (1998) Phys. Rev. A, 57, p. 3589Bauschlicher, C.W., (1980) J. Chem. Phys., 72, p. 880(1998) CRC Handbook of Chemistry and Physics, , 79th ed., edited by D. R.Lide (CRC, Boca Raton, FLSueoka, O., Mori, S., (1989) J. Phys. B, 22, p. 963Panajotovic, R., Jelisavcic, M., Kajita, R., Tanaka, T., Kitajima, M., Cho, H., Tanaka, H., Buckman, S.J., (2004) J. Chem. Phys., 121, p. 4559Winstead, C., Sun, Q., McKoy, V., (1992) J. Chem. Phys., 96, p. 4246Kato, H., Makochekanwa, C., Hoshino, M., Kimura, M., Cho, H., Kume, T., Yamamoto, A., Tanaka, H., (2006) Chem. Phys. Lett., 425, p. 1Carlos Jr. J., L., Karl Jr. R., R., Bauer, S.H., (1974) J. Chem. Soc., Faraday Trans. 2, 2, p. 177Chiu, N.S., Burrow, P.D., Jordan, K.D., (1979) Chem. Phys. Lett., 68, p. 121Kimura, M., Sueoka, O., Makochekanwa, C., Kawate, H., Kawada, M., (2001) J. Chem. Phys., 115, p. 744

An observation of spin-valve effects in a semiconductor field effect transistor: a novel spintronic device

We present the first spintronic semiconductor field effect transistor. The injector and collector contacts of this device were made from magnetic permalloy thin films with different coercive fields so that they could be magnetized either parallel or antiparallel to each other in different applied magnetic fields. The conducting medium was a two dimensional electron gas (2DEG) formed in an AlSb/InAs quantum well. Data from this device suggest that its resistance is controlled by two different types of spin-valve effect: the first occurring at the ferromagnet-2DEG interfaces; and the second occuring in direct propagation between contacts.Comment: 4 pages, 2 figure