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Characterization of an MPPC-Based Scintillator Telescope and Measurement of Cosmic Muon Angular Distribution

Sahla Manithottathil, Anuj Gupta, Mudit Kumar, Navaneeth Poonthottathil

Abstract

This report presents the design, characterization, and application of a high-sensitivity optical detection system based on plastic scintillators coupled to Multi-Pixel Photon Counters (MPPCs). The primary objective was to evaluate the performance of MPPCs (Silicon Photomultipliers) as robust, low-voltage alternatives to traditional photomultiplier tubes for detecting faint scintillation light. The optoelectronic properties of the sensors were analyzed, including single-photoelectron gain calibration and dark count rate measurements, to optimize the signal-to-noise ratio. By embedding wavelength-shifting fibers to enhance light collection efficiency, the system was configured into a three-fold coincidence telescope. The angular distribution of the cosmic ray muon flux was measured to validate the detector's stability and geometric acceptance. Fitting the experimental data to a $\bm{\cos^n(θ)}$ distribution yielded an angular exponent of $\bm{n = 1.44 \pm 0.06}$, consistent with literature values. These results demonstrate the efficacy of the MPPC-scintillator coupling for precise photon counting and timing applications in high-energy physics instrumentation.

Characterization of an MPPC-Based Scintillator Telescope and Measurement of Cosmic Muon Angular Distribution

Abstract

This report presents the design, characterization, and application of a high-sensitivity optical detection system based on plastic scintillators coupled to Multi-Pixel Photon Counters (MPPCs). The primary objective was to evaluate the performance of MPPCs (Silicon Photomultipliers) as robust, low-voltage alternatives to traditional photomultiplier tubes for detecting faint scintillation light. The optoelectronic properties of the sensors were analyzed, including single-photoelectron gain calibration and dark count rate measurements, to optimize the signal-to-noise ratio. By embedding wavelength-shifting fibers to enhance light collection efficiency, the system was configured into a three-fold coincidence telescope. The angular distribution of the cosmic ray muon flux was measured to validate the detector's stability and geometric acceptance. Fitting the experimental data to a distribution yielded an angular exponent of , consistent with literature values. These results demonstrate the efficacy of the MPPC-scintillator coupling for precise photon counting and timing applications in high-energy physics instrumentation.
Paper Structure (39 sections, 12 equations, 14 figures, 10 tables)

This paper contains 39 sections, 12 equations, 14 figures, 10 tables.

Table of Contents

  1. Introduction
  2. Theoretical Framework and Apparatus
  3. Theoretical Principles
  4. Muon Interaction with Matter and Energy Loss
  5. Scintillation Detection with Multi-Pixel Photon Counters (MPPCs)
  6. Electrical Characteristics of MPPCs
  7. Electric Gain
  8. Dark Count Rate
  9. The Coincidence Technique for Background Rejection
  10. Models for Muon Angular Distribution
  11. The $\cos^2(\theta)$ Approximation
  12. The General $\cos^n(\theta)$ Model (Pethuraj et al.)
  13. The Shukla & Sankrith Model
  14. The Schwerdt Model
  15. Apparatus
  16. ...and 24 more sections

Figures (14)

  • Figure 1: Schematic representation of a cosmic ray air shower. The primary proton p initiates the cascade. The Muons ($\bm{\mu}$) are highlighted in red as they are the penetrating particles detected in this setup.
  • Figure 2: The complete experimental setup. (a) Laptop station for data acquisition. (b) RIGOL DHO924 oscilloscope. (c) Interface box for bias voltage distribution and signal readout. (d) The three-fold scintillator telescope assembly (containing the scintillators, WLS fibers, and MPPCs). (e) DC power supply. (f) Light-proof black sheet used to cover the detector assembly during operation to ensure complete darkness.
  • Figure 3: Stopping power ($dE/dx$) as a function of muon momentum. The curve shows the characteristic minimum, defining the Minimum Ionizing Particle (MIP) region yau2008cosmic.
  • Figure 4: Photograph of the Hamamatsu MPPC sensors used in the experiment.
  • Figure 5: Conceptual diagram of the three-fold coincidence technique. A valid event is recorded only when a single muon passes through all three detectors simultaneously, generating overlapping electrical pulses. This logic effectively filters out random background noise.
  • ...and 9 more figures