Study of Forbush decreases with a WC detector Luis Villaseor in collaboration with Angelica Bahena UMSNH Symposium CINVESTAV-UNAM In memoriam Augusto Garcia ICN, December 1,2009 Cosmic rays (1912) Forbush effect (1937) Can we see the Forbush effect with a single WCD? Auger (muons)~ 4% (ICRC 2009) McMurdo (neutrons)~ 15% Detectors Volume 1m height by 1.15m diameter. We use a tyvek bag PMT: EMI 8 in to get Difuse reflection Two water tanks Detectors Tipical muon Amplitude ~150 mV ~200 MeV Our threshold 22 mV ~0.15 VEM Stopping muon at 0.1 VEM Decay electron at 0.17 VEM = 41 MeV Crossing muon at 1 VEM Alarcn M. et al., NIM A 420 [1-2], (1999). Auger, NIM 2006 Water Cerenkov Detector Water Cerenkov Detector H.Salazar and L. Villasenor, NIM 2005 Water Cerenkov Detector Electronics We started with two setups CAMAC Discriminator Amplificator Scalers GPIB LabView Electronics GPS Custom-made ADC Pressure and temperature sensors FPGA + VHDL Serial port, Linux tools Electronics One reason Why We prefered Our custom FPGA-based Electronics Baseline Changed Rate did not Change Because our Thresholds Are anchored To the baseline Inside the FPGA Besides Programming FPGAs is fun! Raw Data Data analysis: Anticorrelation Between R and P Data from October, 2009 Data analysis: Anticorrelation Between R and P Data from November, 2009 . Data Analysis Corrected Data Comparison with neutron detector data Conlusions Stable operation of WCD FPGA-based electronics performs well Good anti-correlation of rate with atmospheric pressure at the 0.5% level Our periodic variations 2% We will take data during the upcoming period of solar activity T he answer to our initial question: Yes, provided the sun cooperates