Christopher Walter

Professor of Physics

External Address: 
Box 90305 Physics Department, Duke University, Durham, NC 27710
Internal 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

Research in High Energy Physics at Duke University awarded by Department of Energy (Principal Investigator). 2013 to 2019

CAREER: Optimization of a large water Cherenkov detector for the Deep Underground Science and Engineering Laboratory awarded by National Science Foundation (Principal Investigator). 2009 to 2015

Research in High Energy Physics at Duke University awarded by Department of Energy (Co-Principal Investigator). 1991 to 2013

Research in High Energy Physics at Duke University awarded by Department of Energy (Co-Principal Investigator). 1991 to 2009

Walter, CW. "The super-kamiokande experiment." Neutrino Oscillations: Present Status and Future Plans. January 1, 2008. 19-43. Full Text

Abe, K, Amey, J, Andreopoulos, C, Antonova, M, Aoki, S, Ariga, A, Autiero, D, Ban, S, Barbi, M, Barker, GJ, Barr, G, Barry, C, Bartet-Friburg, P, Batkiewicz, M, Berardi, V, Berkman, S, Bhadra, S, Bienstock, S, Blondel, A, Bolognesi, S, Bordoni, S, Boyd, SB, Brailsford, D, Bravar, A, Bronner, C, Buizza Avanzini, M, Calland, RG, Campbell, T, Cao, S, Cartwright, SL, Catanesi, MG, Cervera, A, Checchia, C, Cherdack, D, Chikuma, N, Christodoulou, G, Clifton, A, Coleman, J, Collazuol, G, and Coplowe, D et al. "Combined Analysis of Neutrino and Antineutrino Oscillations at T2K." Physical review letters 118.15 (April 10, 2017): 151801-. Full Text

Abe, K, Andreopoulos, C, Antonova, M, Aoki, S, Ariga, A, Assylbekov, S, Autiero, D, Ban, S, Barbi, M, Barker, GJ, Barr, G, Bartet-Friburg, P, Batkiewicz, M, Bay, F, Berardi, V, Berkman, S, Bhadra, S, Bienstock, S, Blondel, A, Bolognesi, S, Bordoni, S, Boyd, SB, Brailsford, D, Bravar, A, Bronner, C, Buizza Avanzini, M, Calland, RG, Campbell, T, Cao, S, Caravaca Rodríguez, J, Cartwright, SL, Castillo, R, Catanesi, MG, Cervera, A, Cherdack, D, Chikuma, N, Christodoulou, G, Clifton, A, and Coleman, J et al. "First measurement of the muon neutrino charged current single pion production cross section on water with the T2K near detector." Physical Review D 95.1 (January 2017). Full Text

Abe, K, Haga, Y, Hayato, Y, Ikeda, M, Iyogi, K, Kameda, J, Kishimoto, Y, Miura, M, Moriyama, S, Nakahata, M, Nakajima, T, Nakano, Y, Nakayama, S, Orii, A, Sekiya, H, Shiozawa, M, Takeda, A, Tanaka, H, Tomura, T, Wendell, RA, Akutsu, R, Irvine, T, Kajita, T, Kaneyuki, K, Nishimura, Y, Richard, E, Okumura, K, Labarga, L, Fernandez, P, Gustafson, J, Kachulis, C, Kearns, E, Raaf, JL, Stone, JL, Sulak, LR, Berkman, S, Nantais, CM, Tanaka, HA, Tobayama, S, Goldhaber, M, Kropp, WR, and Mine, S et al. "Search for proton decay via and in exposure of the Super-Kamiokande water Cherenkov detector." Physical Review D 95.1 (January 2017). Full Text

Abe, K, Andreopoulos, C, Antonova, M, Aoki, S, Ariga, A, Assylbekov, S, Autiero, D, Ban, S, Barbi, M, Barker, GJ, Barr, G, Bartet-Friburg, P, Batkiewicz, M, Bay, F, Berardi, V, Berkman, S, Bhadra, S, Blondel, A, Bolognesi, S, Bordoni, S, Boyd, SB, Brailsford, D, Bravar, A, Bronner, C, Buizza Avanzini, M, Calland, RG, Campbell, T, Cao, S, Caravaca Rodríguez, J, Cartwright, SL, Castillo, R, Catanesi, MG, Cervera, A, Cherdack, D, Chikuma, N, Christodoulou, G, Clifton, A, Coleman, J, and Collazuol, G et al. "Measurement of Coherent π^{+} Production in Low Energy Neutrino-Carbon Scattering." Physical review letters 117.19 (November 4, 2016): 192501-. Full Text

Abe, K, Haga, K, Hayato, Y, Ikeda, M, Iyogi, K, Kameda, J, Kishimoto, Y, Miura, M, Moriyama, S, Nakahata, M, Nakajima, T, Nakano, Y, Nakayama, S, Orii, A, Sekiya, H, Shiozawa, M, Takeda, A, Tanaka, H, Tasaka, S, Tomura, T, Akutsu, R, Kajita, T, Kaneyuki, K, Nishimura, Y, Richard, E, Okumura, K, Labarga, L, Fernandez, P, Blaszczyk, FDM, Gustafson, J, Kachulis, C, Kearns, E, Raaf, JL, Stone, JL, Sulak, LR, Berkman, S, Nantais, CM, Tobayama, S, Goldhaber, M, Kropp, WR, Mine, S, and Weatherly, P et al. "SEARCH FOR NEUTRINOS IN SUPER-KAMIOKANDE ASSOCIATED WITH GRAVITATIONAL-WAVE EVENTS GW150914 AND GW151226." The Astrophysical Journal 830.1 (October 10, 2016): L11-L11. Full Text

Olive, KA. "Review of Particle Physics." Chinese Physics C 40.10 (October 2016): 100001-100001. Full Text

Richard, E, Okumura, K, Abe, K, Haga, Y, Hayato, Y, Ikeda, M, Iyogi, K, Kameda, J, Kishimoto, Y, Miura, M, Moriyama, S, Nakahata, M, Nakajima, T, Nakano, Y, Nakayama, S, Orii, A, Sekiya, H, Shiozawa, M, Takeda, A, Tanaka, H, Tomura, T, Wendell, RA, Akutsu, R, Irvine, T, Kajita, T, Kaneyuki, K, Nishimura, Y, Labarga, L, Fernandez, P, Gustafson, J, Kachulis, C, Kearns, E, Raaf, JL, Stone, JL, Sulak, LR, Berkman, S, Nantais, CM, Tanaka, HA, Tobayama, S, Goldhaber, M, Kropp, WR, and Mine, S et al. "Measurements of the atmospheric neutrino flux by Super-Kamiokande: Energy spectra, geomagnetic effects, and solar modulation." Physical Review D 94.5 (September 2016). Full Text

Abe, K, Haga, Y, Hayato, Y, Ikeda, M, Iyogi, K, Kameda, J, Kishimoto, Y, Marti, L, Miura, M, Moriyama, S, Nakahata, M, Nakajima, T, Nakayama, S, Orii, A, Sekiya, H, Shiozawa, M, Sonoda, Y, Takeda, A, Tanaka, H, Takenaga, Y, Tasaka, S, Tomura, T, Ueno, K, Yokozawa, T, Akutsu, R, Irvine, T, Kaji, H, Kajita, T, Kametani, I, Kaneyuki, K, Lee, KP, Nishimura, Y, McLachlan, T, Okumura, K, Richard, E, Labarga, L, Fernandez, P, Blaszczyk, FDM, Gustafson, J, Kachulis, C, Kearns, E, Raaf, JL, and Stone, JL et al. "Solar neutrino measurements in Super-Kamiokande-IV." Physical Review D 94.5 (September 2016). Full Text

Abe, K, Haga, Y, Hayato, Y, Ikeda, M, Iyogi, K, Kameda, J, Kishimoto, Y, Miura, M, Moriyama, S, Nakahata, M, Nakano, Y, Nakayama, S, Sekiya, H, Shiozawa, M, Suzuki, Y, Takeda, A, Tanaka, H, Tomura, T, Ueno, K, Wendell, RA, Yokozawa, T, Irvine, T, Kajita, T, Kametani, I, Kaneyuki, K, Lee, KP, McLachlan, T, Nishimura, Y, Richard, E, Okumura, K, Labarga, L, Fernandez, P, Berkman, S, Tanaka, HA, Tobayama, S, Gustafson, J, Kearns, E, Raaf, JL, Stone, JL, Sulak, LR, Goldhaber, M, and Carminati, G et al. "Real-time supernova neutrino burst monitor at Super-Kamiokande." Astroparticle Physics 81 (August 2016): 39-48. Full Text

Abe, K, Andreopoulos, C, Antonova, M, Aoki, S, Ariga, A, Assylbekov, S, Autiero, D, Barbi, M, Barker, GJ, Barr, G, Bartet-Friburg, P, Batkiewicz, M, Berardi, V, Berkman, S, Bhadra, S, Blondel, A, Bolognesi, S, Bordoni, S, Boyd, SB, Brailsford, D, Bravar, A, Bronner, C, Buizza Avanzini, M, Calland, RG, Cao, S, Caravaca Rodríguez, J, Cartwright, SL, Castillo, R, Catanesi, MG, Cervera, A, Cherdack, D, Chikuma, N, Christodoulou, G, Clifton, A, Coleman, J, Collazuol, G, Cremonesi, L, and Dabrowska, A et al. "Measurement of double-differential muon neutrino charged-current interactions on without pions in the final state using the T2K off-axis beam." Physical Review D 93.11 (June 2016). Full Text

Pages

Rasmussen, A, Guyonnet, A, Lage, C, Antilogus, P, Astier, P, Doherty, P, Gilmore, K, Kotov, I, Lupton, R, Nomerotski, A, O'Connor, P, Stubbs, C, Tyson, A, and Walter, C. "High fidelity point-spread function retrieval in the presence of electrostatic, hysteretic pixel response." January 1, 2016. Full Text

Cravens, P, Hosaka, J, Ishihara, K, Kameda, J, Koshio, Y, Minamino, A, Mitsuda, G, Miura, M, Moriyama, S, Nakahata, M, Namba, T, Obayashi, Y, Shiozawa, M, Suzuki, Y, Takeda, A, Takeuchi, Y, Yamada, S, Higuchi, I, Ishitsuka, M, Kajita, T, Kaneyuki, K, Mitsuka, G, Nakayama, S, Nishino, H, Okada, A, Okumura, K, Saji, C, Takenaga, Y, Clark, S, Desai, S, Kearns, E, Likhoded, S, Stone, JL, Sulak, LR, Wang, W, Goldhaber, M, Casper, D, Cravens, JP, Kropp, WR, Liu, DW, Mine, S, Regis, C, and Smy, MB et al. "Current status of solar neutrinos at super-kamiokande." January 1, 2006.

Cravens, P, Hosaka, J, Ishihara, K, Kameda, J, Koshio, Y, Minamino, A, Mitsuda, G, Miura, M, Moriyama, S, Nakahata, M, Namba, T, Obayashi, Y, Shiozawa, M, Suzuki, Y, Takeda, A, Takeuchi, Y, Yamada, S, Higuchi, I, Ishitsuka, M, Kajita, T, Kaneyuki, K, Mitsuka, G, Nakayama, S, Nishino, H, Okada, A, Okumura, K, Saji, C, Takenaga, Y, Clark, S, Desai, S, Kearns, E, Likhoded, S, Stone, JL, Sulak, LR, Wang, W, Goldhaber, M, Casper, D, Cravens, JP, Kropp, WR, Liu, DW, Mine, S, Regis, C, and Smy, MB et al. "Current status of solar neutrinos at super-kamiokande." American Physical Society, 2006.