VOLUME 81, NUMBER 6 PHYSICAL REVIEW LETTERS 10 AUGUST 1998
Measurements of the Solar Neutrino Flux from Super-Kamiokande’s First 300 Days
Y. Fukuda,
1
T. Hayakawa,
1
E. Ichihara,
1
K. Inoue,
1
K. Ishihara,
1
H. Ishino,
1
Y. Itow,
1
T. Kajita,
1
J. Kameda,
1
S. Kasuga,
1
K. Kobayashi,
1
Y. Kobayashi,
1
Y. Koshio,
1
K. Martens,
1
M. Miura,
1
M. Nakahata,
1
S. Nakayama,
1
A. Okada,
1
M. Oketa,
1
K. Okumura,
1
M. Ota,
1
N. Sakurai,
1
M. Shiozawa,
1
Y. Suzuki,
1
Y. Takeuchi,
1
Y. Totsuka,
1
S. Yamada,
1
M. Earl,
2
A. Habig,
2
J. T. Hong,
2
E. Kearns,
2
S. B. Kim,
2,
* M. Masuzawa,
2, ²
M. D. Messier,
2
K. Scholberg,
2
J. L. Stone,
2
L. R. Sulak,
2
C. W. Walter,
2
M. Goldhaber,
3
T. Barszczak,
4
W. Gajewski,
4
P. G. Halverson,
4, ‡
J. Hsu,
4
W. R. Kropp,
4
L. R. Price,
4
F. Reines,
4
H. W. Sobel,
4
M. R. Vagins,
4
K. S. Ganezer,
5
W. E. Keig,
5
R. W. Ellsworth,
6
S. Tasaka,
7
J. W. Flanagan,
8, ²
A. Kibayashi,
8
J. G. Learned,
8
S. Matsuno,
8
V. Stenger,
8
D. Takemori,
8
T. Ishii,
9
J. Kanzaki,
9
T. Kobayashi,
9
K. Nakamura,
9
K. Nishikawa,
9
Y. Oyama,
9
A. Sakai,
9
M. Sakuda,
9
O. Sasaki,
9
S. Echigo,
10
M. Kohama,
10
A. T. Suzuki,
10
T. J. Haines,
11,4
E. Blaufuss,
12
R. Sanford,
12
R. Svoboda,
12
M. L. Chen,
13
Z. Conner,
13, §
J. A. Goodman,
13
G. W. Sullivan,
13
M. Mori,
14,
J. Hill,
15
C. K. Jung,
15
C. Mauger,
15
C. McGrew,
15
E. Sharkey,
15
B. Viren,
15
C. Yanagisawa,
15
W. Doki,
16
T. Ishizuka,
16, ¶
Y. Kitaguchi,
16
H. Koga,
16
K. Miyano,
16
H. Okazawa,
16
C. Saji,
16
M. Takahata,
16
A. Kusano,
17
Y. Nagashima,
17
M. Takita,
17
T. Yamaguchi,
17
M. Yoshida,
17
M. Etoh,
18
K. Fujita,
18
A. Hasegawa,
18
T. Hasegawa,
18
S. Hatakeyama,
18
T. Iwamoto,
18
T. Kinebuchi,
18
M. Koga,
18
T. Maruyama,
18
H. Ogawa,
18
A. Suzuki,
18
F. Tsushima,
18
M. Koshiba,
19
M. Nemoto,
20
K. Nishijima,
20
T. Futagami,
21
Y. Hayato,
21
Y. Kanaya,
21
K. Kaneyuki,
21
Y. Watanabe,
21
D. Kielczewska,
22,4
R. Doyle,
23
J. George,
23
A. Stachyra,
23
L. Wai,
23
J. Wilkes,
23
and K. Young
23
1
Institute for Cosmic Ray Research, University of Tokyo, Tanashi, Tokyo 188-8502, Japan
2
Department of Physics, Boston University, Boston, Massachusetts 02215
3
Physics Department, Brookhaven National Laboratory, Upton, New York 11973
4
Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-4575
5
Department of Physics, California State University, Dominguez Hills, Carson, California 90747
6
Department of Physics, George Mason University, Fairfax, Virginia 22030
7
Department of Physics, Gifu University, Gifu, Gifu 501-1193, Japan
8
Department of Physics and Astronomy, University of Hawaii, Honolulu, Hawaii 96822
9
Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Tsukuba,
Ibaraki 305-0801, Japan
10
Department of Physics, Kobe University, Kobe, Hyogo 657-8501, Japan
11
Physics Division, P-23, Los Alamos National Laboratory, Los Alamos, New Mexico 87544
12
Physics Department, Louisiana State University, Baton Rouge, Louisiana 70803
13
Department of Physics, University of Maryland, College Park, Maryland 20742
14
Department of Physics, Miyagi University of Education, Sendai, Miyagi 980-0845, Japan
15
Physics Department, State University of New York, Stony Brook, New York 11794-3800
16
Department of Physics, Niigata University, Niigata, Niigata 950-2181, Japan
17
Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
18
Department of Physics, Tohoku University, Sendai, Miyagi 980-8578, Japan
19
The University of Tokyo, Tokyo 113-0033, Japan
20
Department of Physics, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
21
Department of Physics, Tokyo Institute for Technology, Meguro, Tokyo 152-8551, Japan
22
Institute of Experimental Physics, Warsaw University, 00-681 Warsaw, Poland
23
Department of Physics, University of Washington, Seattle, Washington 98195-1560
(Received 15 April 1998)
The first results of the solar neutrino flux measurement from Super-Kamiokande are presented.
The results shown here are obtained from data taken between 31 May 1996, and 23 June 1997.
Using our measurement of recoil electrons with energies above 6.5 MeV, we infer the total flux
of
8
B solar neutrinos to be 2.42 6 0.06stat
10.10
20.07
syst 3 10
6
cm
22
s
21
. This result is consistent
with the Kamiokande measurement and is 36% of the flux predicted by the BP95 solar model.
The flux is also measured in 1.5 month subsets and shown to be consistent with a constant rate.
[S0031-9007(98)06804-5]
PACS numbers: 26.65. + t, 95.85.Ry, 96.40.Tv
The neutrino plays a crucial role in both astrophysics
and particle physics. This Letter is on measurements
of solar neutrinos that are produced in the core of the
Sun through nuclear reaction chains. Since neutrinos pass
through matter largely unimpeded, the mechanism of solar
energy generation taking place at the central core of the
Sun can be studied directly by solar neutrinos. Evidence
of as yet unresolved neutrino properties may also be
1158 0031-9007 98 81(6) 1158(5)$15.00 © 1998 The American Physical Society