Recent Progress

Since March of 1998 we have been running two experiments simultaneously.  The two experiments are determined by the trigger: 1) A trigger every 5 millisec accepts tracks (primarily single) from any station which has a track stored since the last readout; and 2) a multiple track trigger which demands a number, N, stations to be in time coincidence. The former (1) is sensitive to primary cosmic rays with energies from 30 to 300 GeV, and the latter (2) is sensitive to primary energies >= 100 TeV.

Our most recent progress is presented in the following papers available in electronic form from the Los Alamos E-Print Achives:

 
• A Proportional Wire Chamber Array: GRAND's Status*
• Search for Sub-TeV Gamma Rays Coincident with BATSE Gamma Ray Bursts*
• A Study of the Ground Level Event of April 15, 2001 with GRAND*

*These papers were also presented at the 28th International Cosmic Ray Conference at Tsukuba, Japan in August of 2003.
Conference proceedings are available from the conference website


• Ground level muons in coincidence with the solar flare of April 15, 2001

We have also contributed to:
 

• Constraints on Models for TeV Gamma Rays from Gamma-Ray Bursts

The paper "Search for sub-TeV gamma rays in coincidence with gamma ray bursts" by Poirier et al. has been accepted for publication in Physical Review D.

Copies of the papers are also available upon request.  For a complete listing of publications from Project GRAND, see publications.

 A two dimensional display of the deviations of the data from average values in terms of sigma, the standard deviation. The results are given as a function of Declination versus Right Ascension. Although the statistical deviations can be large (+/- 5 sigma), the absolute variations are small (<1%) due to the large numbers of identified single muons in each box.

“Distributions of secondary muons at sea level from cosmic gamma rays below 10 TeV,” J. Poirier, S. Roesler, and A. Fassò, Astroparticle Physics 17, 4, 441-458 (2002).

“Ground level muons in coincidence with the solar flare of April 15, 2001,” J. Poirier and C. D'Andrea, J. Geophys. Res., Space Physics, Vol. 107(A11) 1376-1384 (2002).

“Search for sub-TeV gamma rays in coincidence with gamma ray bursts,” J. Poirier, C. D'Andrea, P.C. Fragile, J. Gress, G.J. Mathews, and D. Race, Phys. Rev. D67, 042001, 1-6 (2003).

“Constraints on models for TeV gamma rays from gamma-ray bursts,” P.C. Fragile, G.J. Mathews, J. Poirier, T. Totani, Astroparticle Physics 20, 591-607 (2004).

“Ground level muons coincident with the 20 January 2005 solar flare,” C. D’Andrea and J. Poirier, Geophys. Res. Lett. 32, L14102 (2005).

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