Ground Detectors for the Study of Cosmic Ray Showers
Luis Villaseor-UMSNH In coll. with the group of Humberto Salazar- BUAP SECOND SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Puebla, Mxico September 7, 2006 Contents Single Liquid Scintillator (LS) Detector
Single Water Cherenkov (WC) Detector Composition of showers with known m/EM and use of neural networks Hybrid EAS-UAP Ground Array to Study CRs with Energies around 1015 eV Conclusions Single Liquid Scintillator (LS)
Detector 35 l liquid Scintillator + 2 inch PMT + simple electronics 1.3 million double-pulse events 2 MeV/cm I~ 1 cm-2 min-1 t1= t =2.208 +- 0.027 ms t2= 1.979 +- 0.039 ms m+/m - =1.28 +-0.06
Gc = t2-1 - t1-1 = ms-1 m+/m - = Measurement of the lifetimes of Pions and Kaons using this simple setup is (maybe) possible Single Water Cherenkov (WC)
Detector Rotoplas Tank Inner D = 1.54 m 8 inch PMT 2200 l distilled water up to 1.2 m (1/5 in volume of Auger tanks) Tyvek used as inside liner Measure Charge, Amplitude,T10-50,T10-90
with good precision for three different triggers. Arbitrary muons threshold of 30 mV ~74 pe LabView based DAS No PMT Glass Cherenkov signal With PMT Glass Cherenkov signal No PMT Glass Cherenkov signal With PMT Glass Cherenkov signal R shower (Q>7VEM) = 1 Hz
Low Charge Peak=0.12 VEM Rmuon = 876 Hz R EM = 80 Hz R shower (Q>7VEM) = 1 Hz Not an Artifact due to V threshold = 0.12 VEM x 240 MeV/VEM = 29 MeV for knock-on electrons Shaded hist. shows electrons selected for Q/A < .5 risetime < .5 With E~ 10.8 MeV Muon Decay in a WC Detector
Raw Data With cut C2 > C1 t = ms = 41 +- 11 MeV for decay electrons Stopping muon at 0.95 VEM
Crossing muon at 1.05 VEM Alarcn M. et al., NIM A 420 [1-2], 39-47 (1999). Composition of showers with known m/EM and use of neural networks Nm/Ne Strongly Correlated With Primary Mass, i.e. ~2 x for Fe wrt p Look here To understand there Use low energy data to get real
m and EM traces to eliminate systematics due to detector simulation Look here To understand there Stopping muon or electron Q~0.12 VEM (9 pe) T12~3ns Isolated Muon
Shower Q>7 VEM (500 pe) T12>15ns 4 muons, 15ns Data trace Q=7.8 VEM 8 muons 15 ns 33 electrons 25 ns Parameters for Data and Composed Events
Charge (VEM) Amplitude (V) T10-50 (ns) T10-90 2 or 3 classes as output (8m, 4m + 33e, 66e)
Training and Clasification Results for a Kohonen Neural Network 4 features as input (Charge, Amplitude, T10-50, T1090) 8 Neurons in first layer 4 in second layer 2 or 3 classesas output (8m, 4m + 33e, 66e) Training and Clasification Results for Two Classes
8 m 4m 33 e Data 65% 39% 68% 35% 61% 32% Class Training and Clasification Results for Two Classes
8 m 0m 66 e Data 65% 33% 78% 35% 67% 22% Class Training and Clasification Results for Three Classes
8 m 0 e 4 m 33 e 0m 66 e Data 56% 29% 33% 58% 21% 35% 27% 15% 0 m 23% 36% 40% Class Conclusions Clear separation of muons, electrons, PMT interactions and showers in a single WCD Rise time 10-50% is linear with Q/V Neural Networks classify composed events of muons and electrons better than randomly Shower data is dominated by muons To do: Apply to Auger with 25 ns sampling time. EAS-UAP Ground Array to Study CRs with Energies around 1015 eV
in coll. WithBUAP: Humberto Salazar, Oscar Martnez, Csar Alvarez + Estudiantes del Grupo de la FCFM-BUAP Facultad deFsico-Matemticas, Benemrita Universidad Autnoma de Puebla, Apartado Postal 1364, Puebla, Pue., 72000, Mxico At an energy of approximately 3 PeV the spectral index steepens (knee).
To understand the reason for the knee, one must understand the source, acceleration mechanism, and propagation of cosmic rays. First-order Fermi acceleration has a cutoff energy (protons to 1014 eV and Iron to 3 x 1015 eV) Observing the mass composition of cosmic rays at the knee therefore provides an important clue to the origin of cosmic rays. Source Supernova shock-wave Fermi acceleration is correct + Unknown mechanism i.e., rotating compact magnetic objects (neutron stars or black holes) at higher energies = kink due to overlap between the two mechanisms with progressive change in chemical composition as the knee is approached. Propagation Smooth energy distribution up to the highest cosmic-ray energies with unknown loss mechanism beginning at about 1015 eV. Measuring the chemical composition of the cosmic rays at 1015 eV can test the different explanations. PMT Electron tubes 9353 K EAS Array(19 N, 90W, 800 g/cm2)Goal:Study energy spectrum, arrival direction and compositin of CRs around the knee: from eV. Area: 4000 m^2 10 Liquid Ssintillator Detectors (Bicron BC-517H) 4 Water Cherenkov Detectors PMT EMI 9030 A 2200m a.s.l., 800 g/cm2. Located at Campus Universidad Autonoma
de Puebla Hybrid: Liquid Scintillator Detectors and water Cherenkov Detectors Energy range 10^14- 10^16 eV EAS-UAP Control Room Home-made DAQ electronics under construction DAQ System Use digital Osciloscopes as ADCs. Rate: 80 eventos/h
Trigger: Coincidence of 3-4 central detectors (40mx40m) NIM y CAMAC. Use digital Osciloscopes as ADCs. Rate: 80 eventos/h DAQ System Calibration Rate: 250 events/m2/s Monitoring Use CAMAC scalers to measure rates of single partcles on each detector. Day-night variations