L. Villaseñor

OBSERVATION OF SMALL-SCALE ANISOTROPY IN THE ARRIVAL DIRECTION DISTRIBUTION OF TeV COSMIC RAYS WITH HAWC

The High-Altitude Water Cherenkov (HAWC) Observatory is sensitive to gamma rays and charged cosmic rays at TeV energies. The detector is still under construction, but data acquisition with the partially deployed detector started in 2013. An analysis of the cosmic-ray arrival direction distribution based on 4.9 × 1010 events recorded between 2013 June and 2014 February shows anisotropy at the 10–4 level on angular scales of about 10°. The HAWC cosmic-ray sky map exhibits three regions of significantly enhanced cosmic-ray flux; two of these regions were first reported by the Milagro experiment. A third region coincides with an excess recently reported by the ARGO-YBJ experiment. An angular power spectrum analysis of the sky shows that all terms up to l = 15 contribute significantly to the excesses.

Search for Gamma-Rays from the Unusually Bright GRB 130427A with the HAWC Gamma-Ray Observatory

The first limits on the prompt emission from the long gamma-ray burst (GRB) 130427A in the >100 GeV energy band are reported. GRB 130427A was the most powerful burst ever detected with a redshift z 0.5 and featured the longest lasting emission above 100 MeV. The energy spectrum extends at least up to 95 GeV, clearly in the range observable by the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory, a new extensive air shower detector currently under construction in central Mexico. The burst occurred under unfavorable observation conditions, low in the sky and when HAWC was running 10% of the final detector. Based on the observed light curve at MeV-GeV energies, eight different time periods have been searched for prompt and delayed emission from this GRB. In all cases, no statistically significant excess of counts has been found and upper limits have been placed. It is shown that a similar GRB close to zenith would be easily detected by the full HAWC detector, which will be completed soon. The detection rate of the full HAWC detector may be as high as one to two GRBs per year. A detection could provide important information regarding the high energy processes at work and the observation of a possible cut-off beyond the Fermi Large Area Telescope energy range could be the signature of gamma-ray absorption, either in the GRB or along the line of sight due to the extragalactic background light.

Search for TeV Gamma-Ray Emission from Point-like Sources in the Inner Galactic Plane with a Partial Configuration of the HAWC Observatory

Author(s): Abeysekara, AU; Alfaro, R; Alvarez, C; Alvarez, JD; Arceo, R; Arteaga-Vela Zquez, JC; Solares, HAA; Barber, AS; Baughman, BM; Bautista-Elivar, N; Reyes, ADB; Belmont, E; Benzvi, SY; Bernal, A; Braun, J; Caballero-Mora, KS; Capistran, T; Carraminana, A; Casanova, S; Castillo, M; Cotti, U; Cotzomi, J; Leon, SCD; Fuente, EDL; Leon, CD; Deyoung, T; Diaz Hernandez, R; Dingus, BL; Duvernois, MA; Ellsworth, RW; Enriquez-Rivera, O; Fiorino, DW; Fraija, N; Garfias, F; Gonzalez, MM; Goodman, JA; Gussert, M; Hampel-Arias, Z; Harding, JP; Hernandez, S; Huntemeyer, P; Hui, CM; Imran, A; Iriarte, A; Karn, P; Kieda, D; Lara, A; Lauer, RJ; Lee, WH; Lennarz, D; Vargas, HL; Linnemann, JT; Longo, M; Raya, GL; Malone, K; Marinelli, A; Marinelli, SS; Martinez, H; Martinez, O; Martinez-Castro, J; Matthews, JA; Miranda-Romagnoli, P; Moreno, E; Mostafa, M; Nellen, L; Newbold, M; Noriega-Papaqui, R; Patricelli, B; Pelayo, R; Perez-Perez, EG; Pretz, J; Ren, Z; Riviere, C; Rosa-Gonzalez, D; Salazar, H; Greus, FS; Sandoval, A; Schneider, M; Sinnis, G; Smith, AJ; Woodle, KS; Springer, RW; Taboada, I; Tibolla, O; Tollefson, K | Abstract:

Space Program KOSMOTEPETL (project KLYPVE and TUS) for the study of extremely high energy cosmic rays

The scientific goal of the KOSMOTEPETL program is to observe and to study ultra high energy cosmic rays through the fluorescent tracks that they produce in the Earth atmosphere with the help of satellite based optical cameras based on the technology of a large mirror-concentrator of light. At low orbits (400–600 km) a mirror with an area of 400 m2 will allow us to observe neutrino induced horizontal tracks starting at the energy threshold of 1 EeV. With these neutrinos, which have to be produced in collisions of extreme energy cosmic rays (with energy >50 EeV) with background photons at distances >100 Mpc, the most distant cosmic ray sources will be revealed. Design of the TUS and KLYPVE detectors (the first detectors of the KOSMOTEPETL program with a mirror area 2 and 10 m2) is presented.

KLYPVE/TUS space experiments for study of ultrahigh-energy cosmic rays

The KLYPVE space experiment has been proposed to study the energy spectrum, composition, and arrival direction of ultrahigh-energy cosmic rays (UHECR) by detecting from satellites the atmosphere fluorescence and scattered Cherenkov light produced by EAS, initiated by UHECR particles. The TUS setup is a prototype KLYPVE instrument. The aim of the TUS experiment is to detect dozens of UHECR events in the energy region of the GZK cutoff, to measure the light background, to test the atmosphere control methods, and to study stability of the optical materials, PMTs, and other instrumental parts in space environment.

ACORDE a Cosmic Ray Detector for ALICE

ACORDE is one of the ALICE detectors, presently under construction at CERN. It consists of an array of plastic scintillator counters placed on the three upper faces of the ALICE magnet. It will act as a cosmic ray trigger, and, together with other ALICE sub-detectors, will provide precise information on cosmic rays with primary energies around 1015–1017eV. Here we describe the design of ACORDE along with the present status and integration into ALICE.

Calibration and monitoring of water Cherenkov detectors with stopping and crossing muons

Abstract The Auger Observatory water Cherenkov detectors (WCD) will require that the initial calibration and subsequent monitoring of each of the WCDs be done in a remote way. We present a method to perform these tasks based on the detection of muons decaying inside the detectors and the application of adequate selection cuts. This technique may be complemented with another based on muons crossing the WCDs. Samples of decaying and crossing muon events were obtained with a WCD prototype to demonstrate the viability of the techniques. Three clear peaks of PMT charge distributions were identified. All of them are useful for calibration and monitoring of WCDs: one for stopping muons, one for decay electrons and one for crossing muons. The mean value of the peak found in the decay-electron charge distribution is 0.18 times the corresponding value for vertically crossing muons; likewise, the mean value of the peak in the charge distribution of crossing muons (excluding corner clipping muons) is 6.1 times the value for decay electrons in a tank of our dimensions; finally, the mean value of the peak in the charge distribution of stopping muons is 0.55 times the value for decay electrons. The techniques described can be applied equally well to unsegmented or segmented Auger tanks as each of the three PMTs of an Auger WCD can be self-triggered independently. The experimental data are well reproduced by numerical simulations.

Electronics for the KLYPVE Detector

The KLYPVE optical detector on board the Russian segment of the ISS will observe 10 thousand km2 of the Earth atmosphere registering the extremely high energy cosmic ray (EHECR) particles producing fluorescent tracks in the atmosphere. In this article the design of the detector is presented, including: the Fresnel type mirror of 10 m2 area, the PMT retina of 2500 pixels, the pixel electronics, the data acquisition electronics, and the trigger system. The detector design is suited to conditions of the space experiment (wide range of temperature, short day-night cycle etc). The problem of selection of rare EHECR events in the presence of high intensity background light is discussed.

PREPARATION OF THE TUS SPACE EXPERIMENT FOR UHECR STUDY

We report on the current status of the TUS space mission project: its goals and the progress achieved so far. The Fresnel mirrors design, performed checks and their production are discussed. Also we discuss our future plans including auxiliary analysis of the fluorescence light yield measured this year by LAPP (Annecy), JINR (Dubna) and LIP (Lisbon) MACFLY Collaboration.

Results from the Puebla extensive air shower detector array

Abstract We describe the design and operation of the first stage of the EAS-UAP extensive air shower array, as a detector of very high energy cosmic rays ( E o > 10 14 eV ). The array is located at the Campus of Puebla University and consists of 18 liquid scintillator detectors, with an active surface of 1 m 2 each and a detector spacing of 20 m in a square grid. In this report we discuss the stability and the calibration of the detector array, as derived from the 10 detectors in operation in the first stage. The main characteristics of the array allow us also to use it as an educational and training facility. First distributions of the arrival direction and the lateral shower srpead are also given.