Christopher Walter

Professor of Physics

Office Location: 
Box 90305 Physics Department, Duke University, Durham, NC 27710
Front Office Address: 
Box 90305, Durham, NC 27708-0305
Phone: 
(919) 660-2535

Overview

My current research program involves studying the properties of the neutrino, a notoriously difficult-to-detect sub-atomic particle. Intriguingly, it is possible that the existence of tiny neutrino masses can be explained by physics of the highest energy scales. These energies cannot be directly approached with accelerators today but existed in the early universe. Neutrinos may hold the imprint of processes in the beginning of our universe that determined the properties of the world today. Studying the nature of the neutrino may help understand what happened during that period. Foremost among the questions I hope to address is ``Why does there seem to be more matter in our universe than anti-matter?'' Neutrino physics is deeply tied to both particle physics and cosmology.

In Japan, I am working on a series of ongoing and future experiments which utilize the Super-Kamiokande (Super-K) detector in the central Japanese Alps. I study both naturally-occurring sources of neutrinos, and neutrinos which we make artificially in accelerators on the other side of Japan. In Super-K, I and my colleagues have published results that proved neutrinos ``oscillate'' between their types and have non-zero mass, overturning a commonly-held belief that they were massless. I followed this work up with the world's first ``long-baseline'' experiment, (the KEK to Kamioka experiment known as K2K), which confirmed that neutrino oscillations were occurring with the same parameters measured in natural sources by using a man-made neutrino beam. Our latest experiment, the Tokai to Kamioka experiment T2K, utilizing Super-K as the long-baseline target, started data-taking in January of 2010 and, in 2011, was the first experiment to find indications of the appearance of “electron-type” neutrinos in a “muon-type” neutrino beam. In 2013 we proved conclusively this transformation was occurring for the first time, thus demonstrating that all three types of neutrinos could change into each other. Utilizing over ten years of data, we also use the Super-K detector to look for evidence of the decay of protons. This would be a monumental discovery and would tell us something about energy scales out of reach of any accelerator we could even think to build.

Looking towards the future I am working on the next generation of giant underground detectors in Japan, the Hyper-Kamiokande experiment. This enormous detector will contain one megaton of water viewed by approximately 100,000 large photo-sensors. Recently, I also have started an effort in observational cosmology, joining a science collaboration for the LSST project, a giant survey telescope that will be located in Chile designed to make a 10 year, three dimensional survey of the entire visible sky. The LSST Dark Energy Science Collaboration will examine billions of galaxies and try to determine the nature of the mysterious “Dark Energy” which is unaccountably causing the universe to pushed apart at a faster and faster rate.

Education & Training

  • Ph.D., California Institute of Technology 1997

  • M.S., California Institute of Technology 1991

  • B.A., University of California at Santa Cruz 1989

Regis, C, Abe, K, Hayato, Y, Iyogi, K, Kameda, J, Koshio, Y, Marti, L, Miura, M, Moriyama, S, Nakahata, M, Nakayama, S, Obayashi, Y, Sekiya, H, Shiozawa, M, Suzuki, Y, Takeda, A, Takenaga, Y, Ueno, K, Yokozawa, T, Kaji, H, Kajita, T, Kaneyuki, K, Lee, KP, Okumura, K, McLachlan, T, Labarga, L, Kearns, E, Raaf, JL, Stone, JL, Sulak, LR, Goldhaber, M, Bays, K, Carminati, G, Kropp, WR, Mine, S, Renshaw, A, Smy, MB, Sobel, HW, Ganezer, KS, Hill, J, Keig, WE, Jang, JS, Kim, JY, Lim, IT, and Albert, JB et al. "Search for proton decay via p→μ+K0 in Super-Kamiokande I, II, and III." Physical Review D - Particles, Fields, Gravitation and Cosmology 86.1 (2012). Full Text

Ueno, K, Abe, K, Hayato, Y, Iida, T, Iyogi, K, Kameda, J, Koshio, Y, Kozuma, Y, Miura, M, Moriyama, S, Nakahata, M, Nakayama, S, Obayashi, Y, Sekiya, H, Shiozawa, M, Suzuki, Y, Takeda, A, Takenaga, Y, Ueshima, K, Yamada, S, Yokozawa, T, Martens, K, Schuemann, J, Vagins, M, Ishihara, C, Kaji, H, Kajita, T, Kaneyuki, K, McLachlan, T, Okumura, K, Shimizu, Y, Tanimoto, N, Kearns, E, Litos, M, Raaf, JL, Stone, JL, Sulak, LR, Bays, K, Kropp, WR, Mine, S, Regis, C, Renshaw, A, Smy, MB, and Sobel, HW et al. "Search for GUT monopoles at Super-Kamiokande." Astroparticle Physics 36.1 (2012): 131-136. Full Text

Nishino, H, Abe, K, Hayato, Y, Iida, T, Ikeda, M, Kameda, J, Koshio, Y, Miura, M, Moriyama, S, Nakahata, M, Nakayama, S, Obayashi, Y, Sekiya, H, Shiozawa, M, Suzuki, Y, Takeda, A, Takenaga, Y, Takeuchi, Y, Ueno, K, Ueshima, K, Watanabe, H, Yamada, S, Hazama, S, Higuchi, I, Ishihara, C, Kaji, H, Kajita, T, Kaneyuki, K, Mitsuka, G, Okumura, K, Tanimoto, N, Dufour, F, Kearns, E, Litos, M, Raaf, JL, Stone, JL, Sulak, LR, Goldhaber, M, Bays, K, Cravens, JP, Kropp, WR, Mine, S, Regis, C, and Smy, MB et al. "Search for nucleon decay into charged antilepton plus meson in Super-Kamiokande i and II." Physical Review D - Particles, Fields, Gravitation and Cosmology 85.11 (2012). Full Text

Beringer, J, Arguin, J-F, Barnett, RM, Copic, K, Dahl, O, Groom, DE, Lin, C-J, Lys, J, Murayama, H, Wohl, CG, Yao, W-M, Zyla, PA, Amsler, C, Antonelli, M, Asner, DM, Baer, H, Band, HR, Basaglia, T, Bauer, CW, Beatty, JJ, Belousov, VI, Bergren, E, Bernardi, G, Bertl, W, Bethke, S, Bichsel, H, Biebel, O, Blucher, E, Blusk, S, Brooijmans, G, Buchmueller, O, Cahn, RN, Carena, M, Ceccucci, A, Chakraborty, D, Chen, M-C, Chivukula, RS, Cowan, G, D'ambrosio, G, Damour, T, Florian, DD, and Gouvêa, AD et al. "Review of particle physics." Physical Review D - Particles, Fields, Gravitation and Cosmology 86.1 (2012). Full Text

Abe, K, Hayato, Y, Iida, T, Ikeda, M, Iyogi, K, Kameda, J, Koshio, Y, Kozuma, Y, Miura, M, Moriyama, S, Nakahata, M, Nakayama, S, Obayashi, Y, Sekiya, H, Shiozawa, M, Suzuki, Y, Takeda, A, Takenaga, Y, Takeuchi, Y, Ueno, K, Ueshima, K, Watanabe, H, Yamada, S, Yokozawa, T, Ishihara, C, Kaji, H, Lee, KP, Kajita, T, Kaneyuki, K, McLachlan, T, Okumura, K, Shimizu, Y, Tanimoto, N, Martens, K, Vagins, MR, Labarga, L, Magro, LM, Dufour, F, Kearns, E, Litos, M, Raaf, JL, Stone, JL, and Sulak, LR et al. "Search for differences in oscillation parameters for atmospheric neutrinos and antineutrinos at Super-Kamiokande." Phys Rev Lett 107.24 (December 9, 2011): 241801-. Full Text

Tremblin, P, Minier, V, Schneider, N, Durand, GA, Ashley, MCB, Lawrence, JS, Luong-Van, DM, Storey, JWV, Durand, GA, Reinert, Y, Veyssiere, C, Walter, C, Ade, P, Calisse, PG, Challita, Z, Fossat, E, Sabbatini, L, Pellegrini, A, Ricaud, P, and Urban, J. "Site testing for submillimetre astronomy at Dome C, Antarctica." Astronomy & Astrophysics 535 (November 2011): A112-A112. Full Text

Abe, K, Abgrall, N, Ajima, Y, Aihara, H, Albert, JB, Andreopoulos, C, Andrieu, B, Aoki, S, Araoka, O, Argyriades, J, Ariga, A, Ariga, T, Assylbekov, S, Autiero, D, Badertscher, A, Barbi, M, Barker, GJ, Barr, G, Bass, M, Bay, F, Bentham, S, Berardi, V, Berger, BE, Bertram, I, Besnier, M, Beucher, J, Beznosko, D, Bhadra, S, Blaszczyk, FDMM, Blondel, A, Bojechko, C, Bouchez, J, Boyd, SB, Bravar, A, Bronner, C, Brook-Roberge, DG, Buchanan, N, Budd, H, Calvet, D, Cartwright, SL, and Carver, A et al. "Indication of electron neutrino appearance from an accelerator-produced off-axis muon neutrino beam." Phys Rev Lett 107.4 (July 22, 2011): 041801-. Full Text Open Access Copy

Abe, K, Hayato, Y, Iida, T, Ikeda, M, Ishihara, C, Iyogi, K, Kameda, J, Kobayashi, K, Koshio, Y, Kozuma, Y, Miura, M, Moriyama, S, Nakahata, M, Nakayama, S, Obayashi, Y, Ogawa, H, Sekiya, H, Shiozawa, M, Suzuki, Y, Takeda, A, Takenaga, Y, Ueno, K, Ueshima, K, Watanabe, H, Yamada, S, Yokozawa, T, Hazama, S, Kaji, H, Kajita, T, Kaneyuki, K, McLachlan, T, Okumura, K, Shimizu, Y, Tanimoto, N, Vagins, MR, Labarga, L, Magro, LM, Dufour, F, Kearns, E, Litos, M, Raaf, JL, Stone, JL, Sulak, LR, and Wang, W et al. "Solar neutrino results in Super-Kamiokande-III." PHYSICAL REVIEW D 83.5 (March 24, 2011). Full Text

Mariani, C, Tornero-Lopez, A, Alcaraz, JL, Andringa, S, Aoki, S, Aoyama, Y, Argyriades, J, Asakura, K, Ashie, R, Berghaus, F, Berns, H, Bhang, H, Blondel, A, Borghi, S, Bouchez, J, Burguet-Castell, J, Casper, D, Catala, J, Cavata, C, Cervera, A, Chen, SM, Cho, KO, Choi, JH, Dore, U, Espinal, X, Fechner, M, Fernandez, E, Fujii, Y, Fukuda, Y, Gomez-Cadenas, J, Gran, R, Hara, T, Hasegawa, M, Hasegawa, T, Hayato, Y, Helmer, RL, Hiraide, K, Hosaka, J, Ichikawa, AK, Iinuma, M, Ikeda, A, and Ishida, T et al. "Measurement of inclusive pi(0) production in the charged-current interactions of neutrinos in a 1.3-GeV wide band beam." PHYSICAL REVIEW D 83.5 (March 16, 2011). Full Text

Mariani, C, Tornero-Lopez, A, Alcaraz, JL, Andringa, S, Aoki, S, Aoyama, Y, Argyriades, J, Asakura, K, Ashie, R, Berghaus, F, Berns, H, Bhang, H, Blondel, A, Borghi, S, Bouchez, J, Burguet-Castell, J, Casper, D, Catala, J, Cavata, C, Cervera, A, Chen, SM, Cho, KO, Choi, JH, Dore, U, Espinal, X, Fechner, M, Fernandez, E, Fujii, Y, Fukuda, Y, Gomez-Cadenas, J, Gran, R, Hara, T, Hasegawa, M, Hasegawa, T, Hayato, Y, Helmer, RL, Hiraide, K, Hosaka, J, Ichikawa, AK, Iinuma, M, Ikeda, A, and Ishida, T et al. "Measurement of inclusive π0 production in the charged-current interactions of neutrinos in a 1.3-GeV wide band beam." Physical Review D - Particles, Fields, Gravitation and Cosmology 83.5 (2011). Full Text

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