Electronics Testing, LArSoft Analysis, and Data Acquisition for MicroBooNE Victor Genty Nevis Labs August 1, 2013 Genty (Nevis) REU Presentations August 1, 2013 1 / 31
Outline 1 Mini & Micro - BooNE 2 Low Energy Excess 3 LArSoft Analysis 4 PMT Gain Study 5 Splitter Reflection 6 PMT Data Acquisition Genty (Nevis) REU Presentations August 1, 2013 2 / 31
MiniBooNE Studied: ν µ → ν e oscillations, both modes With: Cerenkov detector, 950,000 liters of mineral oil, 1520 phototubes in 12-meter diameter sphere Found: Observed data above 475 MeV are consistent with expected background A low energy excess below this energy Genty (Nevis) REU Presentations August 1, 2013 3 / 31
Low Energy Excess Events/MeV Events/MeV Excess events in 200 - 475 MeV 0.6 0.6 +/- ν & ν from µ e e Fit Region +/- ν & ν from K e e 0 neutrino energy region found by ν & ν from K e e 0 π misid 0.4 0.4 ∆ → N γ MiniBooNE. dirt other Constr. Syst. Error Variety of interpretations by Best Fit (E>475MeV) 0.2 0.2 many beyond the Standard Events/MeV Model physics including... 0.3 Data - expected background 3+N Sterile Neutrinos 0.2 Best Fit 2 2 2 sin 2 =0.004, m =1.0eV θ ∆ ... but could be misidentified ν µ 2 2 2 sin 2 θ =0.03, ∆ m =0.3eV 0.1 → can not distinguish e − and γ 0.0 signal -0.1 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.5 1.6 3.0 MicroBooNE detector proposed QE E (GeV) ν to study even lower ν energy A. A. Aguilar-Arevalo et al. (MiniBooNE Collaboration), “Event Excess in the MiniBooNE Search for ¯ ν µ → ¯ ν e Oscillations”, Phys. Rev. Lett. 105, 181801 (2010) Genty (Nevis) REU Presentations August 1, 2013 4 / 31
MicroBooNE - Detector Specifications 170 ton liquid argon cryostat Time Projection Chamber (TPC) with 3 wireplanes 32-40, 8-inch photomultiplier tubes LAr Will study ν e / ¯ ν e appearance Genty (Nevis) REU Presentations August 1, 2013 5 / 31
LArSoft - Detector Simulation LArSoft is a complete set of simulation, reconstruction, and analysis tools for liquid argon detectors Whole detector simulated by GEANT4 (LArG4) Neutrino beams simulated by GENIE, all other particles possible Reconstruction chain developed Event display for three wireplane, can investigate reconstructed parameters → against truth... Genty (Nevis) REU Presentations August 1, 2013 6 / 31
LArSoft - Event Reconstruction Reconstructing neutrino interactions inside MicroBooNE Clustering Raw Data Hits are signal vs time information from a calibrated Wire object and looks for peaks that indicate real Wires energy deposition occurred Calibrated Data Clustering algorithms identify reconstructed wire hits which are correlated both spatially and Hits temporally DBSCAN and Fuzzy Clustering are two such algorithms Clusters Energy Total visible energy deposited on 2D/3D Tracks TPC from e − showers Genty (Nevis) REU Presentations August 1, 2013 7 / 31
LArSoft - Cluster Studies Generate ν e events filter for 1 1 e − + 1 p final states, simple event topology I wrote a LArSoft module, 2 ⇒ MCHitter, to calculate purity and efficiency of reconstructed clusters Compare DBSCAN, 3 FuzzyCluster Efficiency Purity Measures Measures How much of a cluster is composed How many of all hits the particle generated are in a specific cluster of a each true particle If less than 1: algorithm failed to If less than 1: clustering algorithm group the hits created by the could not distinguish true particle particle into a single cluster hits from one another Genty (Nevis) REU Presentations August 1, 2013 8 / 31
LArSoft - Cluster Studies - 1 e − + 1 p PuritiesComb_fuzzy_cut PuritiesComb_db_cut 0.3 0.3 PuritiesComb_fuzzy_cut PuritiesComb_fuzzy_cut PuritiesComb_fuzzy_cut PuritiesComb_db_cut PuritiesComb_db_cut PuritiesComb_db_cut 0.25 0.25 Entries Entries Entries 2897 2897 2897 Entries Entries Entries 2747 2747 2747 Frequency 0.2 Frequency 0.2 0.15 0.15 0.1 0.1 0.05 0.05 0 0 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 Purity Purity EfficienciesComb_fuzzy_cut EfficienciesComb_db_cut 0.3 0.3 EfficienciesComb_fuzzy_cut EfficienciesComb_fuzzy_cut EfficienciesComb_fuzzy_cut EfficienciesComb_db_cut EfficienciesComb_db_cut EfficienciesComb_db_cut 0.25 0.25 Entries Entries Entries 2897 2897 2897 Entries Entries Entries 2747 2747 2747 Frequency Frequency 0.2 0.2 0.15 0.15 0.1 0.1 0.05 0.05 0 0 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 Efficiency Efficiency Genty (Nevis) REU Presentations August 1, 2013 9 / 31
LArSoft - Energy Studies Energy Fraction Counts vs. Energy 5 450 Entries Entries 1000 1000 Mean Mean 0.431 0.431 400 RMS 0.01129 RMS 0.01129 4 ADC Counts × 10 6 350 300 Events 3 250 1 GeV Electron 200 2 150 100 1 50 0 0 0 0.2 0.4 0.6 0.8 1 0 1 2 3 4 5 True e − Energy (GeV) 140 Entries Entries 1000 1000 Mean Mean 0.411 0.411 120 RMS 0.03992 RMS 0.03992 Visible energy fraction ∼ 45% 100 Reconstructed ADC counts from Events 80 hits scaled linearly with true e − 0.5 - 5.0 GeV Electron 60 energy 40 Important for detector calibration 20 0 0 0.2 0.4 0.6 0.8 1 Ionization/True Energy Genty (Nevis) REU Presentations August 1, 2013 10 / 31
MicroBooNE Optical System Phototube array 32-40, 8-inch photomultiplier array located behind TPC wireplanes will collect Argon scintillation The primary importance of the optical systems is for triggering on events Optical information can also contribute to event reconstruction I tested a R5912 8-inch PMT, similar to the ones used in MicroBooNE minus the wavelength shifting coating and single coaxial input. Will be used to study read out electronics Genty (Nevis) REU Presentations August 1, 2013 11 / 31
PMT - Gain Definition Phototube gain is the ratio of secondary electrons collected on the anode to primary electrons ejected from cathode → amplification factor Procedure G ≡ N s Pulse PMT with blue LED @ 100 Hz 1 N p Record mean ( µ v ) peak height and 2 µ v = CGN p standard deviation ( σ v ) of output � σ v = CG N p � voltages, and Vdt over 6000 ⇒ N p = ( µ v /σ v ) 2 triggers Repeat for different input voltages 3 and � Vdt N s = G : Gain eR N s : Number of secondary electrons � 2 � Vdt � σ v N p : Number of primary electrons ⇒ G = µ v eR Genty (Nevis) REU Presentations August 1, 2013 12 / 31
PMT - Gain - Results I Gain vs. Voltage Primary Electrons vs. Voltage 7 100 (100 mV, 20 ns)/DIV (100 mV, 20 ns)/DIV (200 mV, 20 ns)/DIV (200 mV, 20 ns)/DIV 6 (300 mV, 20 ns)/DIV (300 mV, 20 ns)/DIV 80 5 Gain × 10 7 60 4 N p 3 40 2 20 1 0 0 1100 1200 1300 1400 1500 1600 1700 1800 1100 1200 1300 1400 1500 1600 1700 1800 Voltage (V) Voltage (V) Took data at different oscilloscope Number of primary electrons precisions (window size) deviates as function of input voltage Spec. sheets reports gains at 10 7 Should remain constant Optimal operating voltage is 1500 V Photocathode electrons non-poissonian? Interesting gain response at high voltages Genty (Nevis) REU Presentations August 1, 2013 13 / 31
PMT - Gain - Results II Gain vs. Voltage Gain vs. Time 7 7 Measurement Average 6 6 5 5 Gain × 10 7 Gain × 10 7 4 4 3 3 2 2 1 1 0 0 0 5 10 15 20 25 30 35 40 45 1100 1200 1300 1400 1500 1600 1700 1800 Time (min) Voltage (V) Every measurement over 1.5 week Variation in gain at constant period plotted in red, blue square is 1500 V over 40 minutes the average as estimate of Spread is about ± one unit around systematic uncertainty 4 × 10 7 Largest source of systematic uncertainty is the oscilloscope precision Genty (Nevis) REU Presentations August 1, 2013 14 / 31
PMT Splitter - Ringing - Setup A current test of MicroBooNE’s optical system is called Bo. Bo is a liquid argon test chamber for MicroBooNE photomultipliers, cold electronics, high voltage system and much more. An issue arose during electronics testing with the splitter used to split the HV input from the PMT signal, signal reflection observed in shaper V in V out L C 1 C 2 R A simple circuit was used to study the PMT signal reflection between the splitting capacitor C 2 and the PMT base Genty (Nevis) REU Presentations August 1, 2013 15 / 31
PMT Splitter - Ringing - Reflection Why is there reflection? Impedance differentials along the length of the circuit reflect EM signals Splitting circuit, and 50 Ω cable are at different impendances. Toy Circuit Varying L controls the timescale of reflection Varying C 2 controls amplitude No ringing is observed when: L τ circuit = R cable C 2 ≫ τ travel = v signal **Much greater ∼ 3-5 times v signal = 1 foot / 1 . 5 ns L = 4 → 20 meters C 2 = 1 nF → 10 nF Genty (Nevis) REU Presentations August 1, 2013 16 / 31
PMT Splitter - Ringing - Tests Short Cable - Shaper Long Cable - Shaper 30 30 25 25 20 20 Voltage (mV) Voltage (mV) 15 15 10 10 5 5 0 0 -5 -5 -0.5 0 0.5 1 1.5 -0.5 0 0.5 1 1.5 Time ( µ s) Time ( µ s) τ circuit = 50 Ω · 1 nF = 50 ns Short cable L = 4 m τ circuit > τ travel = 4 m · 1 . 5 ns / foot ∼ 20 ns → no ringing Long cable L = 20 m τ circuit ≯ τ travel = 10 m · 1 . 5 ns / foot ∼ 100 ns → yes ringing Genty (Nevis) REU Presentations August 1, 2013 17 / 31
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