New Hot Paper Comment by Edward Kearns

Edward Kearns answers a few questions about this month's new hot paper in the field of Physics. The author has also sent along images of their work.

From •>>September 2006

Field: Physics
Article Title: Measurement of atmospheric neutrino oscillation parameters by Super-Kamiokande I
Authors: Ashie, Y;Hosaka, J;Ishihara, K;Itow, Y;Kameda, J;Koshio, Y;Minamino, A;Mitsuda, C;Miura, M;Moriyama, S;Nakahata, M;Namba, T;Nambu, R;Obayashi, Y;Shiozawa, M;Suzuki, Y;Takeuchi, Y;Taki, K;Yamada, S;Ishitsuka, M;Kajita, T;Kaneyuki, K;Nakayama, S;Okada, A;Okumura, K;Saji, C;Takenaga, Y;Clark, ST;Desai, S;Kearns, E;Likhoded, S;Stone, JL;Sulak, LR;Wang, W;Goldhaber, M;Casper, D;Cravens, JP;Gajewski, W;Kropp, WR;Liu, DW;Mine, S;Smy, MB;Sobel, HW;Sterner, CW;Vagins, MR;Ganezer, KS;Hill, J;Keig, WE;Jang, JS;Kim, JY;Lim, IT;Scholberg, K;Walter, CW;Ellsworth, RW;Tasaka, S;Guillian, G;Kibayashi, A;Learned, JG;Matsuno, S;Takemori, D;Messier, MD;Hayato, Y;Ichikawa, AK;Ishida, T;Ishii, T;Iwashita, T;Kobayashi, T;Maruyama, T;Nakamura, K;Nitta, K;Oyama, Y;Sakuda, M;Totsuka, Y;Suzuki, AT;Hasegawa, M;Hayashi, K;Kato, I;Maesaka, H;Morita, T;Nakaya, T;Nishikawa, K;Sasaki, T;Ueda, S;Yamamoto, S;Haines, TJ;Dazeley, S;Hatakeyama, S;Svoboda, R;Blaufuss, E;Goodman, JA;Sullivan, GW;Turcan, D;Habig, A;Fukuda, Y;Jung, CK;Kato, T;Kobayashi, K;Malek, M;Mauger, C;McGrew, C;Sarrat, A;Sharkey, E;Yanagisawa, C;Toshito, T;Miyano, K;Tamura, N;Ishii, J;Kuno, Y;Yoshida, M;Kim, SB;Yoo, J;Okazawa, H;Ishizuka, T;Choi, Y;Seo, HK;Gando, Y;Hasegawa, T;Inoue, K;Shirai, J;Suzuki, A;Koshiba, M;Nakajima, Y;Nishijima, K;Harada, T;Ishino, H;Watanabe, Y;Kielczewska, D;Zalipska, J;Berns, HG;Gran, R;Shiraishi, KK;Stachyra, A;Washburn, K;Wilkes, RJ
Journal: PHYS REV D
Volume: 71
Issue: 11
Page: art.
Year: no.-112005 JUN 2005
* Univ Tokyo, Inst Cosm Ray Res, Kamioka Observ, Gifu 5061205, Japan.
* Univ Tokyo, Inst Cosm Ray Res, Kamioka Observ, Gifu 5061205, Japan.
* Univ Tokyo, Inst Cosm Ray Res, Res Ctr Cosm Neutrinos, Kashiwa, Chiba 2778582, Japan.
* Boston Univ, Dept Phys, Boston, MA 02215 USA.
* Brookhaven Natl Lab, Dept Phys, Upton, NY 11973 USA.
* Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA.
* Calif State Univ Dominguez Hills, Dept Phys, Carson, CA 90747 USA.
* Chonnam Natl Univ, Dept Phys, Kwangju 500757, South Korea.
* Duke Univ, Dept Phys, Durham, NC 27708 USA.
* George Mason Univ, Dept Phys, Fairfax, VA 22030 USA.
* Gifu Univ, Dept Phys, Gifu 5011193, Japan.
* Univ Hawaii, Dept Phys & Astron, Honolulu, HI 96822 USA.
* Indiana Univ, Dept Phys, Bloomington, IN 47405 USA.
* KEK, High Energy Accelerator Res Org, Tsukuba, Ibaraki 3050801, Japan.
* Kobe Univ, Dept Phys, Kobe, Hyogo 6578501, Japan.
* Kobe Univ, Dept Phys, Kobe, Hyogo 6578502, Japan.
* Los Alamos Natl Lab, Div Phys, Los Alamos, NM 87544 USA.
* Louisiana State Univ, Dept Phys & Astron, Baton Rouge, LA 70803 USA.
* Univ Maryland, Dept Phys, College Pk, MD 20742 USA.
* Univ Minnesota, Dept Phys, Duluth, MN 55812 USA.
* Miyagi Univ Educ, Dept Phys, Sendai, Miyagi 9800845, Japan.
* SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA.
* Nagoya Univ, Dept Phys, Nagakute, Aichi 4648602, Japan.
* Niigata Univ, Dept Phys, Niigata 9502181, Japan.
* Osaka Univ, Dept Phys, Toyonaka, Osaka 5600043, Japan.
* Seoul Natl Univ, Dept Phys, Seoul 151742, South Korea.
* Shizuoka Seika Coll, Shizuoka 4258611, Japan.
* Univ Shizuoka, Dept Syst Engn, Hamamatsu, Shizuoka 4328561, Japan.
* Sungkyunkwan Univ, Dept Phys, Suwon 440746, South Korea.
* Tohoku Univ, Res Ctr Neutrino Sci, Sendai, Miyagi 9808578, Japan.
* Univ Tokyo, Tokyo 1130033, Japan.
* Tokai Univ, Dept Phys, Hiratsuka, Kanagawa 2591292, Japan.
* Tokyo Inst Technol, Dept Phys, Tokyo 1528551, Japan.
* Univ Warsaw, Inst Expt Phys, PL-00681 Warsaw, Poland.
* Univ Washington, Dept Phys, Seattle, WA 98195 USA.

Why do you think this paper is highly cited?

We are in a "golden age" of neutrino physics, thanks to a number of recent results that are revealing the nature of these particles, and also thanks to a number of present and future experiments designed to complete the picture.

This paper presents the best measurement to date of the fundamental parameters of nature that control the phenomenon of neutrino oscillation—for the case of muon neutrinos converting into tau neutrinos.

“...Super-Kamiokande is an enormously massive
detector and by running for 5 years underground we have managed to
detect and measure 10,000 neutrinos from cosmic rays.”

Theoreticians refer to this paper as they attempt to build models that accommodate the measurements; experimentalists refer to this paper as they work to confirm or extend our understanding of the neutrino.

Does it describe a new discovery, methodology, or synthesis of knowledge?

Many would agree that the 1998 results from Super-Kamiokande on atmospheric neutrinos initiated this period of activity, and the paper reporting those results has gone on to become the most-cited experimental particle physics paper, with more than 2,600 citations so far.

This paper is the follow-up: it completes the analysis of the dataset, now nearly three times larger, and combines different data samples in a way to make the most accurate possible measurement of the phenomenon of neutrino oscillation. It is also a lengthy paper, documenting various techniques in considerable detail.

Could you summarize the significance of your paper in layman's terms?

One of the four forces of nature, the weak force, is often accompanied by a very ethereal particle, the neutrino. They are produced in abundance by nuclear reactions in the sun or by nuclear reactors, and by high-energy collisions of cosmic rays or accelerator beams.

Because they are electrically neutral, they pass through matter quite readily and are hard to detect. But Super-Kamiokande is an enormously massive detector and by running for five years underground, we have managed to detect and measure 10,000 neutrinos from cosmic rays.

Our detector easily distinguishes two different flavors of neutrinos (electron and muon flavor) and, by the absence of some interactions, we can tell a lot about the third flavor (tau).

In this data, we observe muon neutrinos disappearing if they travel a long distance, and since we do not see electron neutrinos appear, we conclude they have changed into tau neutrinos. That the neutrinos do this at all tells us that they have mass; previously, it was assumed the neutrino mass was zero.

By measuring the energy and direction of the neutrinos that disappear, we measure the difference in mass (it is tiny) and the probability that they will change flavor (it is very probable).

How did you become involved in this research, and were there obstacles along the way?

This paper is the work of a large number of scientists in the Super-Kamiokande collaboration. Every author became involved in a different way: as graduate students seeking a Ph.D. thesis topic, as researchers who have been pursuing the behavior of neutrinos for many years, and everything in between. What was attractive about this research was the opportunity to decisively resolve the puzzling properties of neutrinos that had been emerging over the previous quarter century.

Are there any social or political implications for your research?

This research is pure fundamental science.

Edward Kearns, PhD
Professor
Department of Physics
Boston University
Boston, MA, USA

A Closer Look...

Below is an image sent in by Edward Kearns which correspond with the featured paper, or current research.

The inside of the Super-Kamiokande detector taken during water filling in May 2006.
The walls are lines with 11,000 photomultiplier tubes.
[Click for an even larger view, 1600x1071]

ESI Special Topics, September 2006
Citing URL - http://www.esi-topics.com/nhp/2006/september-06-EdwardKearns.html