SiStripConstants.h

#pragma once
 
#include <string_view>
 
namespace tracking::digitization {
 
// ---------------------------------------------------------------------------
// Physical constant
// ---------------------------------------------------------------------------
 
inline constexpr double ENERGY_PER_EHP_MEV = 3.62e-6;
 
// ---------------------------------------------------------------------------
// Sensor geometry
// ---------------------------------------------------------------------------
 
inline constexpr double SENSE_PITCH_MM = 0.030;
inline constexpr double READOUT_PITCH_MM = 0.060;
inline constexpr int N_READOUT_STRIPS = 767;
inline constexpr double SIGMA_V_MM = 20.0;
 
// ---------------------------------------------------------------------------
// Sensor operating conditions
// ---------------------------------------------------------------------------
 
inline constexpr double BIAS_VOLTAGE_V = 200.0;
inline constexpr double DEPLETION_VOLTAGE_V = 70.0;
inline constexpr double TEMPERATURE_K = 300.0;
 
// ---------------------------------------------------------------------------
// Readout electronics and sampling
// ---------------------------------------------------------------------------
 
inline constexpr std::string_view PULSE_SHAPE_NAME = "CRRC";
inline constexpr double PEAKING_TIME_NS = 45.0;
inline constexpr double SECOND_TIME_CONST_NS = 10.0;
inline constexpr double SAMPLING_INTERVAL_NS = 25.0;
inline constexpr int N_SAMPLES = 3;
inline constexpr int ADC_BITS = 14;
inline constexpr int ADC_PEDESTAL = 0;
inline constexpr double T0_OFFSET_NS = 0.0;
 
// ---------------------------------------------------------------------------
// Front-end gain and charge-to-ADC conversion (HPS SVT APV25 configuration)
//
// amplitude [ADC] = (charge / MIP_ELECTRONS)
//                 * READOUT_RESISTOR_OHMS * READOUT_INPUT_STAGE_GAIN
//                 * 2^ADC_BITS / ADC_FULL_SCALE_MV
// ---------------------------------------------------------------------------
 
inline constexpr double MIP_ELECTRONS = 25000.0;
inline constexpr double READOUT_RESISTOR_OHMS = 100.0;
inline constexpr double READOUT_INPUT_STAGE_GAIN = 1.5;
inline constexpr double ADC_FULL_SCALE_MV = 2000.0;
 
inline constexpr double ADC_ELECTRONS_PER_COUNT =
    MIP_ELECTRONS / (READOUT_RESISTOR_OHMS * READOUT_INPUT_STAGE_GAIN *
                     (1 << ADC_BITS) / ADC_FULL_SCALE_MV);
 
// ---------------------------------------------------------------------------
// Sense-to-readout charge transfer efficiencies (AC-coupled sensor)
//
// From HPS CDFSiSensorSim / HpsSiSensor.  The transfer_efficiencies matrix
// is {{readoutTransferEfficiency, senseTransferEfficiency}}.
//
// For ratio = readout_pitch / sense_pitch = 2:
//   - Paired sense strips (even index, physically under a readout strip):
//       fraction transferred = READOUT_TRANSFER_EFFICIENCY
//   - Unpaired sense strips (odd index, between two readout strips):
//       fraction transferred to EACH adjacent readout strip
//       = SENSE_TRANSFER_EFFICIENCY  (total ≈ 0.838; ~16% lost)
// ---------------------------------------------------------------------------
 
inline constexpr double READOUT_TRANSFER_EFFICIENCY = 0.986;
inline constexpr double SENSE_TRANSFER_EFFICIENCY = 0.419;
 
// ---------------------------------------------------------------------------
// Electronics noise and readout threshold
// ---------------------------------------------------------------------------
 
inline constexpr double NOISE_ELECTRONS = 1000.0;
inline constexpr double THRESHOLD_ELECTRONS = 3000.0;
 
inline constexpr double NOISE_SIGMA_ADC =
    NOISE_ELECTRONS / ADC_ELECTRONS_PER_COUNT;
inline constexpr double THRESHOLD_ADC =
    THRESHOLD_ELECTRONS / ADC_ELECTRONS_PER_COUNT;
 
}  // namespace tracking::digitization