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1. An All-Sky Search for Steady VHE Gamma-Ray Sources

Author

Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagrito water Cherenkov detector in the Jemez Mountains near Los Alamos, New Mexico took data from February 1997 to April 1998. Milagrito served as a prototype for the larger Milagro detector, which has just begun operations. Milagrito was the first large-aperture gamma-ray detector with sensitivity to gamma rays below 1 TeV. We report here on a search for steady emission from point sources over most of the northern sky using data from Milagrito.

Published
2017

2. Study of the Shadows of the Moon and the Sun with VHE Cosmic Rays

Author

Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Milagrito, a prototype for the Milagro detector, operated for 15 months in 1997-8 and collected 8.9 billion events. It was the first extensive air shower (EAS) array sensitive to showers intiated by primaries with energy below 1 TeV. The shadows of the sun and moon observed with cosmic rays can be used to study systematic pointing shifts and measure the angular resolution of EAS arrays. Below a few TeV, the paths of cosmic rays coming toward the earth are bent by the helio- and geo-magnetic fields. This is expected to distort and displace the shadows of the sun and the moon. The moon shadow, offset from the nominal (undeflected) position, has been observed with high statistical significance in Milagrito. This can be used to establish energy calibrations, as well as to search for the anti-matter content of the VHE cosmic ray flux. The shadow of the sun has also been observed with high significance.

Published
2017

3. Search for Short Duration Bursts of TeV Gamma Rays with the Milagrito Telescope

Author

Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagrito water Cherenkov telescope operated for over a year. The most probable gamma-ray energy was ~1 TeV and the trigger rate was as high as 400 Hz. We have developed an efficient technique for searching the entire sky for short duration bursts of TeV photons. Such bursts may result from "traditional" gamma-ray bursts that were not in the field-of-view of any other instruments, the evaporation of primordial black holes, or some as yet undiscovered phenomenon. We have begun to search the Milagrito data set for bursts of duration 10 seconds. Here we will present the technique and the expected results. Final results will be presented at the conference.

Published
2017

4. Instrumented Water Tanks can Improve Air Shower Detector Sensitivity

Author

Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Previous works have shown that water Cherenkov detectors have superior sensitivity to those of scintillation counters as applied to detecting extensive air showers (EAS). This is in large part due to their much higher sensitivity to EAS photons which are more than five times more numerous than EAS electrons. Large area water Cherenkov detectors can be constructed relatively cheaply and operated reliably. A sparse detector array has been designed which uses these types of detectors to substantially increase the area over which the Milagro Gamma Ray Observatory collects EAS information. Improvements to the Milagro detector's performance characteristics and sensitivity derived from this array and preliminary results from a prototype array currently installed near the Milagro detector will be presented.

Published
2017

5. Search for a TeV Component of GRBs using the Milagrito Detector

Author

Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Observing gamma ray bursts (GRBs) in the TeV energy range can be extremely valuable in providing insight to GRB radiation mechanisms and in constraining source distances. The Milagrito detector was an air shower array which used the water Cherenkov technique to search for TeV sources. Data from this detector was analyzed to look for a TeV component of GRBs coincident with low energy -rays detected by the BATSE instrument on the Compton Gamma Ray Observatory. A sample of 54 BATSE GRBs which were in the field of view of the Milagrito detector during its lifetime (February 1997 to May 1998) was used.

Published
2017

6. Milagrito Detection of TeV Emission from Mrk 501

Author

Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagro water Cherenkov detector near Los Alamos, New Mexico, has been operated as a sky monitor at energies of a few TeV between February 1997 and April 1998. Serving as a test run for the full Milagro detector, Milagrito has taken data during the strong and long-lasting 1997 flare of Mrk 501. We present results from the analysis of Mrk 501 and compare the excess and background rates with expectations from the detector simulations.

Published
2017

7. Calibration of the Milagro Cosmic Ray Telescope

Author

Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagro detector is an air shower array which uses the water Cherenkov technique and is capable of continuously monitoring the sky at energies near 1 TeV. The detector consists of 20000 metric tons of pure water instrumented with 723 photo-multiplier tubes (PMTs). The PMTs are arranged in a two-layer structure on a lattice of 3 m spacing covering 5000 $m^2$ area. The direction of the shower is determined from the relative timing of the PMT signals, necessitating a common time reference and amplitude slewing corrections to improve the time resolution. The calibration system to provide these consists of a pulsed laser driving 30 diffusing light sources deployed in the pond to allow cross-calibration of the PMTs. The system is capable of calibrating times and the pulse-heights from the PMTs using the time-over-threshold technique. The absolute energy scale is provided using single muons passing through the detector. The description of the calibration system of the Milagro detector and its prototype Milagrito will be presented.

Published
2017

8. Status of the Milagro Gamma Ray Observatory

Author

Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagro Gamma Ray Observatory is the world's first large-area water Cherenkov detector capable of continuously monitoring the sky at TeV energies. Located in northern New Mexico, Milagro will perform an all sky survey of the Northern Hemisphere at energies between ~250 GeV and 50 TeV. With a high duty cycle, large detector area (~5000 square meters), and a wide field-of-view (~1 sr), Milagro is uniquely capable of searching for transient and DC sources of high-energy gamma-ray emission. Milagro has been operating since February, 1999. The current status of the Milagro Observatory and initial results will be discussed.

Published
2017

9. Search for n-n ¯ oscillation in Super-Kamiokande SEARCH FOR n-n ¯ OSCILLATION IN SUPER-⋯ K. ABE et al.

Author

Abe, K, Abe, K, Hayato, Y, Iida, T, Ishihara, K, Kameda, J, Koshio, Y, Minamino, A, Mitsuda, C, Miura, M, Moriyama, S, Nakahata, M, Obayashi, Y, Ogawa, H, Sekiya, H, Shiozawa, M, Suzuki, Y, Takeda, A, Takeuchi, Y, Ueshima, K, Watanabe, H, Higuchi, I, Ishihara, C, Ishitsuka, M, Kajita, T, Kaneyuki, K, Mitsuka, G, Nakayama, S, Nishino, H, Okumura, K, Saji, C, Takenaga, Y, Clark, S, Desai, S, Dufour, F, Herfurth, A, Kearns, E, Likhoded, S, Litos, M, Raaf, JL, Stone, JL, Sulak, LR, Wang, W, Goldhaber, M, Casper, D, Cravens, JP, Dunmore, J, Griskevich, J, Kropp, WR, Liu, DW, Mine, S, Regis, C, Smy, MB, Sobel, HW, Vagins, MR, Ganezer, KS, Hartfiel, B, Hill, J, Keig, WE, Jang, JS, Jeoung, IS, Kim, JY, Lim, IT, Scholberg, K, Tanimoto, N, Walter, CW, Wendell, R, Ellsworth, RW, Tasaka, S, Guillian, G, Learned, JG, Matsuno, S, Messier, MD, Ichikawa, AK, Ishida, T, Ishii, T, Iwashita, T, Kobayashi, T, Nakadaira, T, Nakamura, K, Nishikawa, K, Nitta, K, Oyama, Y, Suzuki, AT, Hasegawa, M, Maesaka, H, Nakaya, T, Sasaki, T, Sato, H, Tanaka, H, Yamamoto, S, Yokoyama, M, Haines, TJ, Dazeley, S, Hatakeyama, S, Svoboda, R, Sullivan, GW, Gran, R, Habig, A, Fukuda, Y, Itow, Y, Abe, K, Abe, K, Hayato, Y, Iida, T, Ishihara, K, Kameda, J, Koshio, Y, Minamino, A, Mitsuda, C, Miura, M, Moriyama, S, Nakahata, M, Obayashi, Y, Ogawa, H, Sekiya, H, Shiozawa, M, Suzuki, Y, Takeda, A, Takeuchi, Y, Ueshima, K, Watanabe, H, Higuchi, I, Ishihara, C, Ishitsuka, M, Kajita, T, Kaneyuki, K, Mitsuka, G, Nakayama, S, Nishino, H, Okumura, K, Saji, C, Takenaga, Y, Clark, S, Desai, S, Dufour, F, Herfurth, A, Kearns, E, Likhoded, S, Litos, M, Raaf, JL, Stone, JL, Sulak, LR, Wang, W, Goldhaber, M, Casper, D, Cravens, JP, Dunmore, J, Griskevich, J, Kropp, WR, Liu, DW, Mine, S, Regis, C, Smy, MB, Sobel, HW, Vagins, MR, Ganezer, KS, Hartfiel, B, Hill, J, Keig, WE, Jang, JS, Jeoung, IS, Kim, JY, Lim, IT, Scholberg, K, Tanimoto, N, Walter, CW, Wendell, R, Ellsworth, RW, Tasaka, S, Guillian, G, Learned, JG, Matsuno, S, Messier, MD, Ichikawa, AK, Ishida, T, Ishii, T, Iwashita, T, Kobayashi, T, Nakadaira, T, Nakamura, K, Nishikawa, K, Nitta, K, Oyama, Y, Suzuki, AT, Hasegawa, M, Maesaka, H, Nakaya, T, Sasaki, T, Sato, H, Tanaka, H, Yamamoto, S, Yokoyama, M, Haines, TJ, Dazeley, S, Hatakeyama, S, Svoboda, R, Sullivan, GW, Gran, R, Habig, A, Fukuda, Y, and Itow, Y

Abstract

A search for neutron-antineutron (n-n¯) oscillation was undertaken in Super-Kamiokande using the 1489 live-day or 2.45×1034 neutron-year exposure data. This process violates both baryon and baryon minus lepton numbers by an absolute value of two units and is predicted by a large class of hypothetical models where the seesaw mechanism is incorporated to explain the observed tiny neutrino masses and the matter-antimatter asymmetry in the Universe. No evidence for n-n¯ oscillation was found; the lower limit of the lifetime for neutrons bound in O16, in an analysis that included all of the significant sources of experimental uncertainties, was determined to be 1.9×1032years at the 90% confidence level. The corresponding lower limit for the oscillation time of free neutrons was calculated to be 2.7×108s using a theoretical value of the nuclear suppression factor of 0.517×1023s-1 and its uncertainty.

Published
2015

10. Search for n-n ¯ oscillation in Super-Kamiokande SEARCH FOR n-n ¯ OSCILLATION IN SUPER-⋯ K. ABE et al.

Author

Abe, K, Abe, K, Hayato, Y, Iida, T, Ishihara, K, Kameda, J, Koshio, Y, Minamino, A, Mitsuda, C, Miura, M, Moriyama, S, Nakahata, M, Obayashi, Y, Ogawa, H, Sekiya, H, Shiozawa, M, Suzuki, Y, Takeda, A, Takeuchi, Y, Ueshima, K, Watanabe, H, Higuchi, I, Ishihara, C, Ishitsuka, M, Kajita, T, Kaneyuki, K, Mitsuka, G, Nakayama, S, Nishino, H, Okumura, K, Saji, C, Takenaga, Y, Clark, S, Desai, S, Dufour, F, Herfurth, A, Kearns, E, Likhoded, S, Litos, M, Raaf, JL, Stone, JL, Sulak, LR, Wang, W, Goldhaber, M, Casper, D, Cravens, JP, Dunmore, J, Griskevich, J, Kropp, WR, Liu, DW, Mine, S, Regis, C, Smy, MB, Sobel, HW, Vagins, MR, Ganezer, KS, Hartfiel, B, Hill, J, Keig, WE, Jang, JS, Jeoung, IS, Kim, JY, Lim, IT, Scholberg, K, Tanimoto, N, Walter, CW, Wendell, R, Ellsworth, RW, Tasaka, S, Guillian, G, Learned, JG, Matsuno, S, Messier, MD, Ichikawa, AK, Ishida, T, Ishii, T, Iwashita, T, Kobayashi, T, Nakadaira, T, Nakamura, K, Nishikawa, K, Nitta, K, Oyama, Y, Suzuki, AT, Hasegawa, M, Maesaka, H, Nakaya, T, Sasaki, T, Sato, H, Tanaka, H, Yamamoto, S, Yokoyama, M, Haines, TJ, Dazeley, S, Hatakeyama, S, Svoboda, R, Sullivan, GW, Gran, R, Habig, A, Fukuda, Y, Itow, Y, Abe, K, Abe, K, Hayato, Y, Iida, T, Ishihara, K, Kameda, J, Koshio, Y, Minamino, A, Mitsuda, C, Miura, M, Moriyama, S, Nakahata, M, Obayashi, Y, Ogawa, H, Sekiya, H, Shiozawa, M, Suzuki, Y, Takeda, A, Takeuchi, Y, Ueshima, K, Watanabe, H, Higuchi, I, Ishihara, C, Ishitsuka, M, Kajita, T, Kaneyuki, K, Mitsuka, G, Nakayama, S, Nishino, H, Okumura, K, Saji, C, Takenaga, Y, Clark, S, Desai, S, Dufour, F, Herfurth, A, Kearns, E, Likhoded, S, Litos, M, Raaf, JL, Stone, JL, Sulak, LR, Wang, W, Goldhaber, M, Casper, D, Cravens, JP, Dunmore, J, Griskevich, J, Kropp, WR, Liu, DW, Mine, S, Regis, C, Smy, MB, Sobel, HW, Vagins, MR, Ganezer, KS, Hartfiel, B, Hill, J, Keig, WE, Jang, JS, Jeoung, IS, Kim, JY, Lim, IT, Scholberg, K, Tanimoto, N, Walter, CW, Wendell, R, Ellsworth, RW, Tasaka, S, Guillian, G, Learned, JG, Matsuno, S, Messier, MD, Ichikawa, AK, Ishida, T, Ishii, T, Iwashita, T, Kobayashi, T, Nakadaira, T, Nakamura, K, Nishikawa, K, Nitta, K, Oyama, Y, Suzuki, AT, Hasegawa, M, Maesaka, H, Nakaya, T, Sasaki, T, Sato, H, Tanaka, H, Yamamoto, S, Yokoyama, M, Haines, TJ, Dazeley, S, Hatakeyama, S, Svoboda, R, Sullivan, GW, Gran, R, Habig, A, Fukuda, Y, and Itow, Y

Abstract

A search for neutron-antineutron (n-n¯) oscillation was undertaken in Super-Kamiokande using the 1489 live-day or 2.45×1034 neutron-year exposure data. This process violates both baryon and baryon minus lepton numbers by an absolute value of two units and is predicted by a large class of hypothetical models where the seesaw mechanism is incorporated to explain the observed tiny neutrino masses and the matter-antimatter asymmetry in the Universe. No evidence for n-n¯ oscillation was found; the lower limit of the lifetime for neutrons bound in O16, in an analysis that included all of the significant sources of experimental uncertainties, was determined to be 1.9×1032years at the 90% confidence level. The corresponding lower limit for the oscillation time of free neutrons was calculated to be 2.7×108s using a theoretical value of the nuclear suppression factor of 0.517×1023s-1 and its uncertainty.

Published
2015

11. First results of a study of TeV emission from GRBs in Milagrito

Author

Miller, RS, Miller, RS, Atkins, R, Benbow, W, Berley, D, Chen, ML, Coyne, DG, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, McConnell, M, McCullough, JF, McEnery, JE, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Shen, B, Shoup, A, Sinnis, C, Smith, AJ, Sullivan, GW, Tumer, T, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Miller, RS, Miller, RS, Atkins, R, Benbow, W, Berley, D, Chen, ML, Coyne, DG, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, McConnell, M, McCullough, JF, McEnery, JE, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Shen, B, Shoup, A, Sinnis, C, Smith, AJ, Sullivan, GW, Tumer, T, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Milagrito, a detector sensitive to gamma-rays at TeV energies, monitored the northern sky during the period February 1997 through May 1998. With a large field of view and high duty cycle, this instrument was used to perform a search for TeV counterparts to gamma-ray bursts. Within the Milagrito field of view 54 gamma-ray bursts at keV energies were observed by the Burst And Transient Satellite Experiment (BATSE) aboard the Compton Gamma-Ray Observatory. This paper describes the results of a preliminary analysis to search for TeV emission correlated with BATSE detected bursts. Milagrito detected an excess of events coincident both spatially and temporally with GRB 970417a, with chance probability $2.8 \times 10^{-5}$ within the BATSE error radius. No other significant correlations were detected. Since 54 bursts were examined the chance probability of observing an excess with this significance in any of these bursts is $1.5 \times 10^{-3}$. The statistical aspects and physical implications of this result are discussed.

Published
2000

12. First results of a study of TeV emission from GRBs in Milagrito

Author

Miller, RS, Atkins, R, Benbow, W, Berley, D, Chen, ML, Coyne, DG, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, McConnell, M, McCullough, JF, McEnery, JE, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Shen, B, Shoup, A, Sinnis, C, Smith, AJ, Sullivan, GW, Tumer, T, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Miller, RS, Atkins, R, Benbow, W, Berley, D, Chen, ML, Coyne, DG, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, McConnell, M, McCullough, JF, McEnery, JE, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Shen, B, Shoup, A, Sinnis, C, Smith, AJ, Sullivan, GW, Tumer, T, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Milagrito, a detector sensitive to gamma-rays at TeV energies, monitored the northern sky during the period February 1997 through May 1998. With a large field of view and high duty cycle, this instrument was used to perform a search for TeV counterparts to gamma-ray bursts. Within the Milagrito field of view 54 gamma-ray bursts at keV energies were observed by the Burst And Transient Satellite Experiment (BATSE) aboard the Compton Gamma-Ray Observatory. This paper describes the results of a preliminary analysis to search for TeV emission correlated with BATSE detected bursts. Milagrito detected an excess of events coincident both spatially and temporally with GRB 970417a, with chance probability $2.8 \times 10^{-5}$ within the BATSE error radius. No other significant correlations were detected. Since 54 bursts were examined the chance probability of observing an excess with this significance in any of these bursts is $1.5 \times 10^{-3}$. The statistical aspects and physical implications of this result are discussed.

Published
2000

13. First results of a study of TeV emission from GRBs in Milagrito

Author

Miller, RS, Miller, RS, Atkins, R, Benbow, W, Berley, D, Chen, ML, Coyne, DG, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, McConnell, M, McCullough, JF, McEnery, JE, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Shen, B, Shoup, A, Sinnis, C, Smith, AJ, Sullivan, GW, Tumer, T, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Miller, RS, Miller, RS, Atkins, R, Benbow, W, Berley, D, Chen, ML, Coyne, DG, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, McConnell, M, McCullough, JF, McEnery, JE, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Shen, B, Shoup, A, Sinnis, C, Smith, AJ, Sullivan, GW, Tumer, T, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Milagrito, a detector sensitive to gamma-rays at TeV energies, monitored the northern sky during the period February 1997 through May 1998. With a large field of view and high duty cycle, this instrument was used to perform a search for TeV counterparts to gamma-ray bursts. Within the Milagrito field of view 54 gamma-ray bursts at keV energies were observed by the Burst And Transient Satellite Experiment (BATSE) aboard the Compton Gamma-Ray Observatory. This paper describes the results of a preliminary analysis to search for TeV emission correlated with BATSE detected bursts. Milagrito detected an excess of events coincident both spatially and temporally with GRB 970417a, with chance probability $2.8 \times 10^{-5}$ within the BATSE error radius. No other significant correlations were detected. Since 54 bursts were examined the chance probability of observing an excess with this significance in any of these bursts is $1.5 \times 10^{-3}$. The statistical aspects and physical implications of this result are discussed.

Published
2000

14. Search for Short Duration Bursts of TeV Gamma Rays with the Milagrito Telescope

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagrito water Cherenkov telescope operated for over a year. The most probable gamma-ray energy was ~1 TeV and the trigger rate was as high as 400 Hz. We have developed an efficient technique for searching the entire sky for short duration bursts of TeV photons. Such bursts may result from "traditional" gamma-ray bursts that were not in the field-of-view of any other instruments, the evaporation of primordial black holes, or some as yet undiscovered phenomenon. We have begun to search the Milagrito data set for bursts of duration 10 seconds. Here we will present the technique and the expected results. Final results will be presented at the conference.

Published
1999

15. Search for a TeV Component of GRBs using the Milagrito Detector

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Observing gamma ray bursts (GRBs) in the TeV energy range can be extremely valuable in providing insight to GRB radiation mechanisms and in constraining source distances. The Milagrito detector was an air shower array which used the water Cherenkov technique to search for TeV sources. Data from this detector was analyzed to look for a TeV component of GRBs coincident with low energy -rays detected by the BATSE instrument on the Compton Gamma Ray Observatory. A sample of 54 BATSE GRBs which were in the field of view of the Milagrito detector during its lifetime (February 1997 to May 1998) was used.

Published
1999

16. Detection of 6 November 1997 Ground Level Event by Milagrito

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Solar Energetic Particles from the 6 November 1997 solar flare/CME(coronal mass ejection) with energies exceeding 10 GeV have been detected by Milagrito, a prototype of the Milagro Gamma Ray Observatory. While particle acceleration beyond 1 GeV at the Sun is well established, few data exist for protons or ions beyond 10 GeV. The Milagro observatory, a ground based water Cherenkov detector designed for observing very high energy gamma ray sources, can also be used to study the Sun. Milagrito, which operated for approximately one year in 1997/98, was sensitive to solar proton and neutron fluxes above ~5- 10 GeV. Milagrito operated in a scaler mode, which was primarily sensitive to muons, low energy photons, and electrons, and the detector operated in a mode sensitive to showers and high zenith angle muons. In its scaler mode, Milagrito registered a rate increase coincident with the 6 November 1997 ground level event observed by Climax and other neutron monitors. A preliminary analysis suggests the presence of >10 GeV particles.

Published
1999

17. Status of the Milagro Gamma Ray Observatory

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagro Gamma Ray Observatory is the world's first large-area water Cherenkov detector capable of continuously monitoring the sky at TeV energies. Located in northern New Mexico, Milagro will perform an all sky survey of the Northern Hemisphere at energies between ~250 GeV and 50 TeV. With a high duty cycle, large detector area (~5000 square meters), and a wide field-of-view (~1 sr), Milagro is uniquely capable of searching for transient and DC sources of high-energy gamma-ray emission. Milagro has been operating since February, 1999. The current status of the Milagro Observatory and initial results will be discussed.

Published
1999

18. An All-Sky Search for Steady VHE Gamma-Ray Sources

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagrito water Cherenkov detector in the Jemez Mountains near Los Alamos, New Mexico took data from February 1997 to April 1998. Milagrito served as a prototype for the larger Milagro detector, which has just begun operations. Milagrito was the first large-aperture gamma-ray detector with sensitivity to gamma rays below 1 TeV. We report here on a search for steady emission from point sources over most of the northern sky using data from Milagrito.

Published
1999

19. Milagrito Detection of TeV Emission from Mrk 501

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagro water Cherenkov detector near Los Alamos, New Mexico, has been operated as a sky monitor at energies of a few TeV between February 1997 and April 1998. Serving as a test run for the full Milagro detector, Milagrito has taken data during the strong and long-lasting 1997 flare of Mrk 501. We present results from the analysis of Mrk 501 and compare the excess and background rates with expectations from the detector simulations.

Published
1999

20. Instrumented Water Tanks can Improve Air Shower Detector Sensitivity

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Previous works have shown that water Cherenkov detectors have superior sensitivity to those of scintillation counters as applied to detecting extensive air showers (EAS). This is in large part due to their much higher sensitivity to EAS photons which are more than five times more numerous than EAS electrons. Large area water Cherenkov detectors can be constructed relatively cheaply and operated reliably. A sparse detector array has been designed which uses these types of detectors to substantially increase the area over which the Milagro Gamma Ray Observatory collects EAS information. Improvements to the Milagro detector's performance characteristics and sensitivity derived from this array and preliminary results from a prototype array currently installed near the Milagro detector will be presented.

Published
1999

21. Calibration of the Milagro Cosmic Ray Telescope

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagro detector is an air shower array which uses the water Cherenkov technique and is capable of continuously monitoring the sky at energies near 1 TeV. The detector consists of 20000 metric tons of pure water instrumented with 723 photo-multiplier tubes (PMTs). The PMTs are arranged in a two-layer structure on a lattice of 3 m spacing covering 5000 $m^2$ area. The direction of the shower is determined from the relative timing of the PMT signals, necessitating a common time reference and amplitude slewing corrections to improve the time resolution. The calibration system to provide these consists of a pulsed laser driving 30 diffusing light sources deployed in the pond to allow cross-calibration of the PMTs. The system is capable of calibrating times and the pulse-heights from the PMTs using the time-over-threshold technique. The absolute energy scale is provided using single muons passing through the detector. The description of the calibration system of the Milagro detector and its prototype Milagrito will be presented.

Published
1999

22. Study of the Shadows of the Moon and the Sun with VHE Cosmic Rays

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Milagrito, a prototype for the Milagro detector, operated for 15 months in 1997-8 and collected 8.9 billion events. It was the first extensive air shower (EAS) array sensitive to showers intiated by primaries with energy below 1 TeV. The shadows of the sun and moon observed with cosmic rays can be used to study systematic pointing shifts and measure the angular resolution of EAS arrays. Below a few TeV, the paths of cosmic rays coming toward the earth are bent by the helio- and geo-magnetic fields. This is expected to distort and displace the shadows of the sun and the moon. The moon shadow, offset from the nominal (undeflected) position, has been observed with high statistical significance in Milagrito. This can be used to establish energy calibrations, as well as to search for the anti-matter content of the VHE cosmic ray flux. The shadow of the sun has also been observed with high significance.

Published
1999

23. Search for Short Duration Bursts of TeV Gamma Rays with the Milagrito Telescope

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagrito water Cherenkov telescope operated for over a year. The most probable gamma-ray energy was ~1 TeV and the trigger rate was as high as 400 Hz. We have developed an efficient technique for searching the entire sky for short duration bursts of TeV photons. Such bursts may result from "traditional" gamma-ray bursts that were not in the field-of-view of any other instruments, the evaporation of primordial black holes, or some as yet undiscovered phenomenon. We have begun to search the Milagrito data set for bursts of duration 10 seconds. Here we will present the technique and the expected results. Final results will be presented at the conference.

Published
1999

24. Search for a TeV Component of GRBs using the Milagrito Detector

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Observing gamma ray bursts (GRBs) in the TeV energy range can be extremely valuable in providing insight to GRB radiation mechanisms and in constraining source distances. The Milagrito detector was an air shower array which used the water Cherenkov technique to search for TeV sources. Data from this detector was analyzed to look for a TeV component of GRBs coincident with low energy -rays detected by the BATSE instrument on the Compton Gamma Ray Observatory. A sample of 54 BATSE GRBs which were in the field of view of the Milagrito detector during its lifetime (February 1997 to May 1998) was used.

Published
1999

25. Calibration of the Milagro Cosmic Ray Telescope

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagro detector is an air shower array which uses the water Cherenkov technique and is capable of continuously monitoring the sky at energies near 1 TeV. The detector consists of 20000 metric tons of pure water instrumented with 723 photo-multiplier tubes (PMTs). The PMTs are arranged in a two-layer structure on a lattice of 3 m spacing covering 5000 $m^2$ area. The direction of the shower is determined from the relative timing of the PMT signals, necessitating a common time reference and amplitude slewing corrections to improve the time resolution. The calibration system to provide these consists of a pulsed laser driving 30 diffusing light sources deployed in the pond to allow cross-calibration of the PMTs. The system is capable of calibrating times and the pulse-heights from the PMTs using the time-over-threshold technique. The absolute energy scale is provided using single muons passing through the detector. The description of the calibration system of the Milagro detector and its prototype Milagrito will be presented.

Published
1999

26. Status of the Milagro Gamma Ray Observatory

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagro Gamma Ray Observatory is the world's first large-area water Cherenkov detector capable of continuously monitoring the sky at TeV energies. Located in northern New Mexico, Milagro will perform an all sky survey of the Northern Hemisphere at energies between ~250 GeV and 50 TeV. With a high duty cycle, large detector area (~5000 square meters), and a wide field-of-view (~1 sr), Milagro is uniquely capable of searching for transient and DC sources of high-energy gamma-ray emission. Milagro has been operating since February, 1999. The current status of the Milagro Observatory and initial results will be discussed.

Published
1999

27. Study of the Shadows of the Moon and the Sun with VHE Cosmic Rays

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Milagrito, a prototype for the Milagro detector, operated for 15 months in 1997-8 and collected 8.9 billion events. It was the first extensive air shower (EAS) array sensitive to showers intiated by primaries with energy below 1 TeV. The shadows of the sun and moon observed with cosmic rays can be used to study systematic pointing shifts and measure the angular resolution of EAS arrays. Below a few TeV, the paths of cosmic rays coming toward the earth are bent by the helio- and geo-magnetic fields. This is expected to distort and displace the shadows of the sun and the moon. The moon shadow, offset from the nominal (undeflected) position, has been observed with high statistical significance in Milagrito. This can be used to establish energy calibrations, as well as to search for the anti-matter content of the VHE cosmic ray flux. The shadow of the sun has also been observed with high significance.

Published
1999

28. Instrumented Water Tanks can Improve Air Shower Detector Sensitivity

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Previous works have shown that water Cherenkov detectors have superior sensitivity to those of scintillation counters as applied to detecting extensive air showers (EAS). This is in large part due to their much higher sensitivity to EAS photons which are more than five times more numerous than EAS electrons. Large area water Cherenkov detectors can be constructed relatively cheaply and operated reliably. A sparse detector array has been designed which uses these types of detectors to substantially increase the area over which the Milagro Gamma Ray Observatory collects EAS information. Improvements to the Milagro detector's performance characteristics and sensitivity derived from this array and preliminary results from a prototype array currently installed near the Milagro detector will be presented.

Published
1999

29. Milagrito Detection of TeV Emission from Mrk 501

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagro water Cherenkov detector near Los Alamos, New Mexico, has been operated as a sky monitor at energies of a few TeV between February 1997 and April 1998. Serving as a test run for the full Milagro detector, Milagrito has taken data during the strong and long-lasting 1997 flare of Mrk 501. We present results from the analysis of Mrk 501 and compare the excess and background rates with expectations from the detector simulations.

Published
1999

30. An All-Sky Search for Steady VHE Gamma-Ray Sources

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

The Milagrito water Cherenkov detector in the Jemez Mountains near Los Alamos, New Mexico took data from February 1997 to April 1998. Milagrito served as a prototype for the larger Milagro detector, which has just begun operations. Milagrito was the first large-aperture gamma-ray detector with sensitivity to gamma rays below 1 TeV. We report here on a search for steady emission from point sources over most of the northern sky using data from Milagrito.

Published
1999

31. Detection of 6 November 1997 Ground Level Event by Milagrito

Author

Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, Yodh, GB, Atkins, R, Atkins, R, Benbow, W, Berley, D, Chen, M-L, Coyne, DG, Delay, RS, Dingus, BL, Dorfan, DE, Ellsworth, RW, Evans, D, Falcone, A, Fleysher, L, Fleysher, R, Gisler, G, Goodman, JA, Haines, TJ, Hoffman, CM, Hugenberger, S, Kelley, LA, Leonor, I, Macri, J, McConnell, M, McCullough, JF, McEnery, JE, Miller, RS, Mincer, AI, Morales, MF, Nemethy, P, Ryan, JM, Schneider, M, Shen, B, Shoup, A, Sinnis, G, Smith, AJ, Sullivan, GW, Thompson, TN, Tumer, OT, Wang, K, Wascko, MO, Westerhoff, S, Williams, DA, Yang, T, and Yodh, GB

Abstract

Solar Energetic Particles from the 6 November 1997 solar flare/CME(coronal mass ejection) with energies exceeding 10 GeV have been detected by Milagrito, a prototype of the Milagro Gamma Ray Observatory. While particle acceleration beyond 1 GeV at the Sun is well established, few data exist for protons or ions beyond 10 GeV. The Milagro observatory, a ground based water Cherenkov detector designed for observing very high energy gamma ray sources, can also be used to study the Sun. Milagrito, which operated for approximately one year in 1997/98, was sensitive to solar proton and neutron fluxes above ~5- 10 GeV. Milagrito operated in a scaler mode, which was primarily sensitive to muons, low energy photons, and electrons, and the detector operated in a mode sensitive to showers and high zenith angle muons. In its scaler mode, Milagrito registered a rate increase coincident with the 6 November 1997 ground level event observed by Climax and other neutron monitors. A preliminary analysis suggests the presence of >10 GeV particles.

Published
1999

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