LSTS-04#

The design model can be found here: LSTS-design.

Parameters shown in bold and italics are specific to each telescope. Parameters without emphasis are inherited from the design model.

Structure#

Parameter Name

Parameter Version

Values

Short Description

array_element_position_ground

2.0.0

-105.06 m, 1.15 m, 33.0 m

Ground coordinate position of an array element.

array_element_position_utm

2.0.0

366822.0 m, 7269361.0 m, 2164.0 m

UTM coordinate position of an array element.

axes_offsets

1.0.0

0.0 cm, 0.0 cm

Geometric offsets to be used in case that the azimuth, altitude, and optical axes do not intersect at the reference point.

camera_body_diameter

1.0.0

348.0 cm

Diameter of camera body (used to account for effects of shadowing). Flat-to-flat for square and hexagonal shapes.

camera_body_shape

1.0.0

2

Camera body shape parameter (used to account for effects of shadowing).

camera_depth

1.0.0

0.0 cm

Depth of the camera body (used to account for effects of shadowing).

dish_shape_length

1.0.0

2800.0 cm

Dish curvature length, best equal to focal length.

effective_focal_length

2.0.0

2923.7 cm, 0.0 cm, 0.0 cm, 0.0 cm, 0.0 cm

Effective focal length. Only to be used for image analysis, has no effect on the simulation.

focal_length

1.0.0

2800.0 cm

Nominal overall focal length of the entire telescope.

focus_offset

1.0.0

6.55 cm, 0.0 deg, 0.0 , 0.0

Distance of the starlight focus from the camera pixels (light guides) entry.

mirror_align_random_distance

1.0.0

0.0 cm

Gaussian r.m.s. spread of random fluctuations in the aligned mirror distance from the focus.

mirror_align_random_horizontal

2.0.0

0.0019 deg, 28.0 deg, 0.0 , 0.0

Gaussian r.m.s. spread of random fluctuations of the mirror alignment angle with respect to nominal alignment in the horizontal component.

mirror_align_random_vertical

2.0.0

0.0019 deg, 28.0 deg, 0.0 , 0.0

Gaussian r.m.s. spread of random fluctuations of the mirror alignment angle with respect to nominal alignment in the vertical component.

mirror_class

1.0.0

0

Parameter to control the type of mirror used (DC, parabolic or SC).

mirror_degraded_reflection

2.0.0

0.8

Mirror degradation factor (wavelength independent).

mirror_focal_length

1.0.0

0.0 cm

Standard focal length of mirror tiles.

mirror_list

2.0.0

mirror_CTA-S-LST_v2020-04-07_rotated.dat

List of mirror positions, diameters, focal lengths, and shape codes.

mirror_offset

1.0.0

93.25 cm

Offset of mirror back plane from fixed point of telescope mount or from the altitude rotation axis, along the direction of the optical axis.

mirror_reflection_random_angle

2.0.0

0.0075 deg, 0.22 , 0.022 deg

Gaussian r.m.s. spread of random fluctuations of microscopic reflection angles due to small-scale surface deviations.

mirror_reflectivity

1.0.0

ref_LST_2020-04-23.dat

Mirror reflectivity measured directly on the facet as function of wavelength. For dual mirror telescopes without explicit reflectivity table given for the secondary, this reflectivity given here is applied twice.

optics_properties

1.0.0

ray-tracing-South-LST-D-d10.0-za20.0_validate_optics.ecsv

Derived properties of the telescope optics.

parabolic_dish

1.0.0

True

Parabolic dish shape is used.

random_focal_length

1.0.0

0.0 cm, 0.0 cm

The spread of random fluctuations in mirror focal lengths.

telescope_axis_height

1.0.0

16.0 m

Height of telescope elevation axis above ground level.

telescope_random_angle

1.0.0

0.0 deg

Random (known) misalignment of the telescope in each axis (Gaussian r.m.s.). The resulting telescope pointing including this misalignment are saved as telescope azimuth and altitude pointing directions.

telescope_random_error

1.0.0

0.0 deg

Random (unknown) alignment error of the telescope in each axis (Gaussian r.m.s.). The resulting telescope pointing including this misalignment is not saved to the simulation output.

telescope_sphere_radius

1.0.0

12.5 m

Telescope fiducial sphere radius.

telescope_transmission

1.0.0

0.969 , 0.0 , 0.0 , 0.0 , 0.0 , 0.0

Off-axis angle-dependent transmission, accounting for absorption and shadowing by masts.

Camera#

Parameter Name

Parameter Version

Values

Short Description

asum_clipping

1.0.0

9999.0 mV

The amplitude level at which the signal from each pixel (after optional shaping) is clipped for its contribution to the analog sum trigger.

asum_offset

1.0.0

0.0 ns

Offset in time where shaping convolution is done.

asum_threshold

2.0.0

260.7 mV

The amplitude level above which an analog sum leads to a telescope trigger.

camera_config_file

1.0.0

camera_CTA-LST-234_analogsum21_v2020-04-14.dat

Definition of pixel types, positions, status (on/off), relative gain (w.r.t the provided gain) and quantum/photodetector efficiency scaling (scale the provided quantum/photodetector efficiency distribution, ignoring wavelength dependence).

camera_degraded_efficiency

1.0.0

1.0

Camera efficiency degradation factor (wavelength independent).

camera_filter

1.0.0

transmission_lst_window_No7-10_ave.dat

Wavelength dependence of the camera transmission, possibly as a function of incidence angle.

camera_pixels

1.0.0

1855

Number of pixels in the camera.

camera_transmission

1.0.0

1.0

Global wavelength-independent transmission factor of the camera, including any plexiglass window.

channels_per_chip

1.0.0

4

Number of channels per readout chip.

default_trigger

1.0.0

AnalogSum

Trigger algorithm used.

disc_ac_coupled

1.0.0

True

Control AC coupling of the discriminators.

disc_bins

1.0.0

68

Number of time bins used for the discriminator simulation.

disc_start

1.0.0

3

Number of time bins by which the discriminator simulation is ahead of the FADC readout.

discriminator_amplitude

1.0.0

6.5 mV

Signal amplitude after amplifier per mean p.e. at the input of the discriminators/comparators.

discriminator_fall_time

1.0.0

1.0 ns

Fall time of the discriminator output after the logical output is reset to false.

discriminator_gate_length

1.0.0

2.0 ns

Effective discriminator gate length.

discriminator_hysteresis

1.0.0

0.0 mV

Value of the discriminator hysteresis.

discriminator_output_amplitude

1.0.0

42.0 mV

The nominal output amplitude of a pixel discriminator as seen at the trigger group coincidence unit.

discriminator_output_var_percent

1.0.0

10.0 %

Channel-to-channel variation (Gaussian r.m.s.) of the output amplitude of a pixel discriminator.

discriminator_pulse_shape

2.0.0

LST_pulse_shape_7dynode_high_intensity_pix1s.dat

Pulse shape at the discriminator/comparator of an individual pixel.

discriminator_rise_time

1.0.0

1.0 ns

Rise time of the discriminator output. The output signal rises linearly within time frame.

discriminator_scale_threshold

1.0.0

1.0

Discriminator/comparator threshold scale factor.

discriminator_sigsum_over_threshold

1.0.0

0.0 mV ns

Integrated signal required over threshold.

discriminator_threshold

1.0.0

99999.0 mV

Discriminator/comparator threshold.

discriminator_time_over_threshold

1.0.0

1.5 ns

Time over threshold required before logic response switches to true.

discriminator_var_gate_length

1.0.0

0.1 ns

Variation of gate length (Gaussian r.m.s).

discriminator_var_sigsum_over_threshold

1.0.0

0.0 mV ns

Gaussian r.m.s. spread of discriminator_sigsum_over_threshold (Pixel-to-pixel variation).

discriminator_var_threshold

1.0.0

0.2 mV

Channel-to-channel variation of discriminator threshold.

discriminator_var_time_over_threshold

1.0.0

0.1 ns

Pixel-to-pixel variation of the time over threshold required before logic response switches to true.

fadc_ac_coupled

1.0.0

True

AC coupling of the FADCs.

fadc_amplitude

1.0.0

25.0 ct

Peak amplitude above pedestal for a photo electron with average signal.

fadc_bins

1.0.0

75

Number of FADC bins to be simulated.

fadc_compensate_pedestal

1.0.0

-1

Emulation of FADC pedestal compensation.

fadc_err_compensate_pedestal

1.0.0

0.0

R.M.S. error on the pedestal evaluation for the compensation step.

fadc_err_pedestal

1.0.0

0.5 ct

Assumed error in initial calibration of pedestal (affects only the reported pedestal).

fadc_lg_amplitude

1.0.0

1.28 ct

Peak amplitude above pedestal for a photo electron with average signal (low-gain channels).

fadc_lg_compensate_pedestal

1.0.0

-1

Emulation of FADC pedestal compensation.

fadc_lg_err_compensate_pedestal

1.0.0

-1.0

R.M.S. error on the pedestal evaluation for the compensation step.

fadc_lg_err_pedestal

1.0.0

0.3 ct

Assumed error in initial calibration of pedestal (low-gain channels; affects only the reported pedestal).

fadc_lg_max_signal

1.0.0

4288 ct

Maximum value of digitized signal per sample (low-gain channels).

fadc_lg_noise

1.0.0

5.7 ct

Gaussian r.m.s. spread of white noise per time bin in digitisation (low-gain channels).

fadc_lg_pedestal

1.0.0

400.0 ct

(F)ADC pedestal value per time slice (low-gain channels).

fadc_lg_sensitivity

1.0.0

-1.0 ct / mV

FADC counts per mV voltage (for low-gain channels).

fadc_lg_sysvar_pedestal

1.0.0

-1.0 ct

Systematic common variations of pedestals (low-gain channels).

fadc_lg_var_pedestal

1.0.0

0.4 ct

Channel-to-channel (or pixel-to-pixel) variation of the pedestal per FADC time slice (low-gain channels). Value is the r.m.s. of the randomly chosen pedestal values around the FADC pedestal.

fadc_lg_var_sensitivity

1.0.0

-1.0

Relative variations in sensitivity (even for FADCs of the same channel; low-gain channels).

fadc_max_signal

1.0.0

4249 ct

Maximum value of digitized signal per sample.

fadc_max_sum

1.0.0

16777215 ct

The maximum value of a pulse sum produced by hardware pulse summation, in sum mode rather than recording pulse samples.

fadc_mhz

1.0.0

1024.0 MHz

FADC sampling rate.

fadc_noise

1.0.0

6.7 ct

Gaussian r.m.s. spread of white noise per time bin in digitization.

fadc_pedestal

1.0.0

400.0 ct

(F)ADC pedestal value per time slice (for high-gain channel for dual-gain readout).

fadc_pulse_shape

2.0.0

LST_pulse_shape_7dynode_high_intensity_pix1s.dat

(F)ADC pulse shape (amplitude vs time).

fadc_sensitivity

1.0.0

1.0 ct / mV

FADC counts per mV voltage.

fadc_sum_bins

1.0.0

40

Number of bins read out in sampled data or summed up in ADC sum data. Corresponds to the experimental length of the readout window.

fadc_sum_offset

1.0.0

9

Number of bins before telescope trigger where summing or reading of sampled data starts.

fadc_sysvar_pedestal

1.0.0

0.04 ct

Systematic common variations of pedestals.

fadc_var_pedestal

1.0.0

0.4 ct

Channel-to-channel (or pixel-to-pixel) variation of the pedestal per FADC time slice. Value is the r.m.s. of the randomly chosen pedestal values around the FADC pedestal (for high-gain channel for dual-gain readout.

fadc_var_sensitivity

2.0.0

0.09

Relative variations in sensitivity (even for FADCs of the same channel).

flatfielding

1.0.0

True

If enabled, the gains in pixels are adjusted to achieve the same signal from the same illumination. If disabled, the gains are adjusted to have equal single-p.e. amplitudes.

gain_variation

1.0.0

0.0187

Fractional gain variation between different photo detectors after adjusting the voltage to have approximately the same gain in all channels.

hg_lg_variation

1.0.0

0.0

Relative pixel-to-pixel variation of the ratio of high-gain to low-gain amplitudes.

lightguide_efficiency_vs_incidence_angle

1.0.0

CTA-LST_lightguide_eff_2020-04-12_average.dat

Lightguide efficiency as a function of incidence angle.

multiplicity_offset

1.0.0

-0.5

Actual threshold of the telescope trigger, adjusted relative to the number of required pixels.

muon_mono_threshold

1.0.0

0 , 0

Thresholds for mono muon events.

nsb_autoscale_airmass

1.0.0

0.84 , 0.29

NSB scaling as function of airmass (zenith angle).

nsb_offaxis

1.0.0

0.0 , 0.0 , 0.0 cm, 0.0 , 0.0

Fall-off of NSB with off-axis angle due to off-axis angle- dependent effective optical area.

nsb_pixel_rate

2.0.0

all: 0.244637 GHz

Number of photo-electrons per nanosecond per pixel due to nightsky background.

num_gains

1.0.0

2

Number of different gains the input signal gets digitized.

only_triggered_telescopes

1.0.0

True

Switch to read out non-triggered telescopes.

pedestal_events

1.0.0

0

Number of pedestal events at start of run with camera lid open (same NSB as for normal events).

photon_delay

1.0.0

19.0 ns

Additional delay added to the arrival times of all photons at the photo sensors.

pixeltrg_time_step

1.0.0

0.0 ns

Time difference between telescope and pixel trigger recording.

pm_average_gain

1.0.0

40000.0

Photo detector average gain. Used to determine the DC currents from night-sky background (NSB) pixel rates.

pm_collection_efficiency

1.0.0

1.0

Photoelectron collection efficiency at the first stage of the photo detector.

pm_gain_index

1.0.0

3.92

PMT gain g and voltage U are assumed to be related by the PMT gain index p through \(g \propto U^{p}\). Used only for PMT timing.

pm_photoelectron_spectrum

2.0.0

spe_LST_2022-04-27_AP2.0e-4.dat

Single photoelectron (p.e.) response distribution (takes into account afterpulsing and the photoelectron collection efficiency for PMT cameras).

pm_transit_time

1.0.0

20.89 ns, 9.0 ns, 350.0 V, 1135.0 V

Total transit time of the photodetector at the average voltage.

pm_voltage_variation

1.0.0

0.03

Fractional high voltage variation, used to adjust the transit time variations (\(\propto 1/\sqrt(V)\)).

qe_variation

2.0.0

0.063

Variation of quantum or photon detection efficiency (Gaussian r.m.s. spread of random fluctuations) between photo detectors in a given camera. Given in fraction of the average quantum or photon detection efficiency; the variation is applied independent of the wavelength.

quantum_efficiency

1.0.0

qe_lst2-4_20200318_high+low.dat

Quantum or photon detection efficiency averaged over all pixels per camera. Random pixel-to-pixel variations are calculated using the qe_variation parameter. Pixel-to-pixel differences in detection efficiency using scaling factors can be specified in the camera_config_file.

random_mono_probability

2.0.0

0.01

Fraction of random mono events to pass stereo selection.

teltrig_min_sigsum

1.0.0

7.8 mV ns

Minimum signal sum at sector trigger over threshold.

teltrig_min_time

1.0.0

0.5 ns

Minimum time of sector trigger over threshold.

transit_time_calib_error

1.0.0

0.0 ns

Accuracy with which the actual signal delay due to transit time variation and corresponding compensation can be determined.

transit_time_compensate_error

1.0.0

0.0 ns

Additional error (r.m.s.) in how well the number of steps for transit time compensation can be determined before the compensation is applied.

transit_time_compensate_step

1.0.0

0.0 ns

If signal delays can be compensated independent of the sampling, this is the time step in which this compensation can be done. A value of zero means no compensation is applied. The same compensation is applied to all channels.

transit_time_error

1.0.0

0.0 ns

Errors (r.m.s.) in transit time, not related to high voltage.

transit_time_jitter

1.0.0

0.7 ns

Time jitter (Gaussian r.m.s. spread of random fluctuations) of individual photo-electrons.

trigger_current_limit

1.0.0

20.0 uA

Pixels above this limit are excluded from the trigger.

trigger_delay_compensation

1.0.0

0.0 ns, 0.0 ns, 0.0 ns, 0.0 ns

The delay applied to the trigger output to compensate for the different execution times of each trigger algorithm.

trigger_pixels

1.0.0

3

Number of pixels required for single telescope trigger.