/***********************************************************************//**
* @brief Return simulated list of events
*
* @param[in] obs Observation.
* @param[in] ran Random number generator.
* @return Pointer to list of simulated events (needs to be de-allocated by
* client)
*
* @exception GException::invalid_argument
* No CTA event list found in observation.
*
* Draws a sample of events from the background model using a Monte
* Carlo simulation. The pointing information, the energy boundaries and the
* good time interval for the sampling will be extracted from the observation
* argument that is passed to the method. The method also requires a random
* number generator of type GRan which is passed by reference, hence the
* state of the random number generator will be changed by the method.
*
* The method also applies a deadtime correction using a Monte Carlo process,
* taking into account temporal deadtime variations. For this purpose, the
* method makes use of the time dependent GObservation::deadc method.
***************************************************************************/
GCTAEventList* GCTAModelBackground::mc(const GObservation& obs, GRan& ran) const
{
// Initialise new event list
GCTAEventList* list = new GCTAEventList;
// Continue only if model is valid)
if (valid_model()) {
// Extract event list to access the ROI, energy boundaries and GTIs
const GCTAEventList* events = dynamic_cast<const GCTAEventList*>(obs.events());
if (events == NULL) {
std::string msg = "No CTA event list found in observation.\n" +
obs.print();
throw GException::invalid_argument(G_MC, msg);
}
// Get simulation region
const GCTARoi& roi = events->roi();
const GEbounds& ebounds = events->ebounds();
const GGti& gti = events->gti();
// Set simulation region for result event list
list->roi(roi);
list->ebounds(ebounds);
list->gti(gti);
// Loop over all energy boundaries
for (int ieng = 0; ieng < ebounds.size(); ++ieng) {
// Initialise de-allocation flag
bool free_spectral = false;
// Set pointer to spectral model
GModelSpectral* spectral = m_spectral;
// If the spectral model is a diffuse cube then create a node
// function spectral model that is the product of the diffuse
// cube node function and the spectral model evaluated at the
// energies of the node function
GModelSpatialDiffuseCube* cube =
dynamic_cast<GModelSpatialDiffuseCube*>(m_spatial);
if (cube != NULL) {
// Set MC simulation cone based on ROI
cube->set_mc_cone(roi.centre().dir(), roi.radius());
// Allocate node function to replace the spectral component
GModelSpectralNodes* nodes = new GModelSpectralNodes(cube->spectrum());
for (int i = 0; i < nodes->nodes(); ++i) {
GEnergy energy = nodes->energy(i);
double intensity = nodes->intensity(i);
double norm = m_spectral->eval(energy, events->tstart());
nodes->intensity(i, norm*intensity);
}
// Signal that node function needs to be de-allocated later
free_spectral = true;
// Set the spectral model pointer to the node function
spectral = nodes;
} // endif: spatial model was a diffuse cube
// Compute the background rate in model within the energy boundaries
// from spectral component (units: cts/s).
// Note that the time here is ontime. Deadtime correction will be done
// later.
double rate = spectral->flux(ebounds.emin(ieng), ebounds.emax(ieng));
// Debug option: dump rate
#if defined(G_DUMP_MC)
std::cout << "GCTAModelBackground::mc(\"" << name() << "\": ";
std::cout << "rate=" << rate << " cts/s)" << std::endl;
#endif
// Loop over all good time intervals
for (int itime = 0; itime < gti.size(); ++itime) {
// Get Monte Carlo event arrival times from temporal model
GTimes times = m_temporal->mc(rate,
gti.tstart(itime),
gti.tstop(itime),
ran);
// Get number of events
int n_events = times.size();
// Reserve space for events
if (n_events > 0) {
list->reserve(n_events);
}
// Loop over events
for (int i = 0; i < n_events; ++i) {
// Apply deadtime correction
double deadc = obs.deadc(times[i]);
if (deadc < 1.0) {
if (ran.uniform() > deadc) {
continue;
}
}
// Get Monte Carlo event energy from spectral model
GEnergy energy = spectral->mc(ebounds.emin(ieng),
ebounds.emax(ieng),
times[i],
ran);
// Get Monte Carlo event direction from spatial model
GSkyDir dir = spatial()->mc(energy, times[i], ran);
// Allocate event
GCTAEventAtom event;
// Set event attributes
event.dir(GCTAInstDir(dir));
event.energy(energy);
event.time(times[i]);
// Append event to list if it falls in ROI
if (events->roi().contains(event)) {
list->append(event);
}
} // endfor: looped over all events
} // endfor: looped over all GTIs
// Free spectral model if required
if (free_spectral) delete spectral;
} // endfor: looped over all energy boundaries
} // endif: model was valid
// Return
return list;
}
/***********************************************************************//**
* @brief Simulate source events from photon list
*
* @param[in] obs Pointer on CTA observation.
* @param[in] models Model list.
* @param[in] ran Random number generator.
* @param[in] wrklog Pointer to logger.
*
* Simulate source events from a photon list for a given CTA observation.
* The events are stored in as event list in the observation.
*
* This method does nothing if the observation pointer is NULL. It also
* verifies if the observation has a valid pointing and response.
***************************************************************************/
void ctobssim::simulate_source(GCTAObservation* obs, const GModels& models,
GRan& ran, GLog* wrklog)
{
// Continue only if observation pointer is valid
if (obs != NULL) {
// If no logger is specified then use the default logger
if (wrklog == NULL) {
wrklog = &log;
}
// Get CTA response
const GCTAResponseIrf* rsp =
dynamic_cast<const GCTAResponseIrf*>(obs->response());
if (rsp == NULL) {
std::string msg = "Response is not an IRF response.\n" +
obs->response()->print();
throw GException::invalid_value(G_SIMULATE_SOURCE, msg);
}
// Get pointer on event list (circumvent const correctness)
GCTAEventList* events =
static_cast<GCTAEventList*>(const_cast<GEvents*>(obs->events()));
// Extract simulation region.
GSkyDir dir = events->roi().centre().dir();
double rad = events->roi().radius() + g_roi_margin;
// Dump simulation cone information
if (logNormal()) {
*wrklog << gammalib::parformat("Simulation area");
*wrklog << m_area << " cm2" << std::endl;
*wrklog << gammalib::parformat("Simulation cone");
*wrklog << "RA=" << dir.ra_deg() << " deg";
*wrklog << ", Dec=" << dir.dec_deg() << " deg";
*wrklog << ", r=" << rad << " deg" << std::endl;
}
// Initialise indentation for logging
int indent = 0;
// Loop over all Good Time Intervals
for (int it = 0; it < events->gti().size(); ++it) {
// Extract time interval
GTime tmin = events->gti().tstart(it);
GTime tmax = events->gti().tstop(it);
// Dump time interval
if (logNormal()) {
if (events->gti().size() > 1) {
indent++;
wrklog->indent(indent);
}
*wrklog << gammalib::parformat("Time interval", indent);
*wrklog << tmin.convert(m_cta_ref);
*wrklog << " - ";
*wrklog << tmax.convert(m_cta_ref);
*wrklog << " s" << std::endl;
}
// Loop over all energy boundaries
for (int ie = 0; ie < events->ebounds().size(); ++ie) {
// Extract energy boundaries
GEnergy emin = events->ebounds().emin(ie);
GEnergy emax = events->ebounds().emax(ie);
// Set true photon energy limits for simulation. If observation
// has energy dispersion then add margin
GEnergy e_true_min = emin;
GEnergy e_true_max = emax;
if (rsp->use_edisp()) {
e_true_min = rsp->ebounds(e_true_min).emin();
e_true_max = rsp->ebounds(e_true_max).emax();
}
// Dump energy range
if (logNormal()) {
if (events->ebounds().size() > 1) {
indent++;
wrklog->indent(indent);
}
*wrklog << gammalib::parformat("Photon energy range", indent);
*wrklog << e_true_min << " - " << e_true_max << std::endl;
*wrklog << gammalib::parformat("Event energy range", indent);
*wrklog << emin << " - " << emax << std::endl;
}
// Loop over all sky models
for (int i = 0; i < models.size(); ++i) {
// Get sky model (NULL if not a sky model)
const GModelSky* model =
dynamic_cast<const GModelSky*>(models[i]);
// If we have a sky model that applies to the present
// observation then simulate events
if (model != NULL &&
model->is_valid(obs->instrument(), obs->id())) {
// Determine duration of a time slice by limiting the
// number of simulated photons to m_max_photons.
// The photon rate is estimated from the model flux
// and used to set the duration of the time slice.
double flux = get_model_flux(model, emin, emax,
dir, rad);
double rate = flux * m_area;
double duration = 1800.0; // default: 1800 sec
if (rate > 0.0) {
duration = m_max_photons / rate;
if (duration < 1.0) { // not <1 sec
duration = 1.0;
}
else if (duration > 180000.0) { // not >50 hr
duration = 180000.0;
}
}
GTime tslice(duration, "sec");
// If photon rate exceeds the maximum photon rate
// then throw an exception
if (rate > m_max_rate) {
std::string modnam = (model->name().length() > 0) ?
model->name() : "Unknown";
std::string msg = "Photon rate "+
gammalib::str(rate)+
" photons/sec for model \""+
modnam+"\" exceeds maximum"
" allowed photon rate of "+
gammalib::str(m_max_rate)+
" photons/sec. Please check"
" the model parameters for"
" model \""+modnam+"\" or"
" increase the value of the"
" hidden \"maxrate\""
" parameter.";
throw GException::invalid_value(G_SIMULATE_SOURCE, msg);
}
// Dump length of time slice and rate
if (logExplicit()) {
*wrklog << gammalib::parformat("Photon rate", indent);
*wrklog << rate << " photons/sec";
if (model->name().length() > 0) {
*wrklog << " [" << model->name() << "]";
}
*wrklog << std::endl;
}
// To reduce memory requirements we split long time
// intervals into several slices.
GTime tstart = tmin;
GTime tstop = tstart + tslice;
// Initialise cumulative photon counters
int nphotons = 0;
// Loop over time slices
while (tstart < tmax) {
// Make sure that tstop <= tmax
if (tstop > tmax) {
tstop = tmax;
}
// Dump time slice
if (logExplicit()) {
if (tmax - tmin > tslice) {
indent++;
wrklog->indent(indent);
}
*wrklog << gammalib::parformat("Time slice", indent);
*wrklog << tstart.convert(m_cta_ref);
*wrklog << " - ";
*wrklog << tstop.convert(m_cta_ref);
*wrklog << " s";
if (model->name().length() > 0) {
*wrklog << " [" << model->name() << "]";
}
*wrklog << std::endl;
}
// Get photons
GPhotons photons = model->mc(m_area, dir, rad,
e_true_min, e_true_max,
tstart, tstop, ran);
// Dump number of simulated photons
if (logExplicit()) {
*wrklog << gammalib::parformat("MC source photons/slice", indent);
*wrklog << photons.size();
if (model->name().length() > 0) {
*wrklog << " [" << model->name() << "]";
}
*wrklog << std::endl;
}
// Simulate events from photons
for (int i = 0; i < photons.size(); ++i) {
// Increment photon counter
nphotons++;
// Simulate event. Note that this method
// includes the deadtime correction.
GCTAEventAtom* event = rsp->mc(m_area,
photons[i],
*obs,
ran);
if (event != NULL) {
// Use event only if it falls within ROI
// energy boundary and time slice
if (events->roi().contains(*event) &&
event->energy() >= emin &&
event->energy() <= emax &&
event->time() >= tstart &&
event->time() <= tstop) {
event->event_id(m_event_id);
events->append(*event);
m_event_id++;
}
delete event;
}
} // endfor: looped over events
// Go to next time slice
tstart = tstop;
tstop = tstart + tslice;
// Reset indentation
if (logExplicit()) {
if (tmax - tmin > tslice) {
indent--;
wrklog->indent(indent);
}
}
} // endwhile: looped over time slices
// Dump simulation results
if (logNormal()) {
*wrklog << gammalib::parformat("MC source photons", indent);
*wrklog << nphotons;
if (model->name().length() > 0) {
*wrklog << " [" << model->name() << "]";
}
*wrklog << std::endl;
*wrklog << gammalib::parformat("MC source events", indent);
*wrklog << events->size();
if (model->name().length() > 0) {
*wrklog << " [" << model->name() << "]";
}
*wrklog << std::endl;
}
} // endif: model was a sky model
} // endfor: looped over models
// Dump simulation results
if (logNormal()) {
*wrklog << gammalib::parformat("MC source events", indent);
*wrklog << events->size();
*wrklog << " (all source models)";
*wrklog << std::endl;
}
// Reset indentation
if (logNormal()) {
if (events->ebounds().size() > 1) {
indent--;
wrklog->indent(indent);
}
}
} // endfor: looped over all energy boundaries
// Reset indentation
if (logNormal()) {
if (events->gti().size() > 1) {
indent--;
wrklog->indent(indent);
}
}
} // endfor: looped over all time intervals
// Reset indentation
wrklog->indent(0);
} // endif: observation pointer was valid
// Return
return;
}
/***********************************************************************//**
* @brief Simulate background events from model
*
* @param[in] obs Pointer on CTA observation.
* @param[in] models Models.
* @param[in] ran Random number generator.
* @param[in] wrklog Pointer to logger.
*
* Simulate background events from models. The events are stored as event
* list in the observation.
*
* This method does nothing if the observation pointer is NULL.
***************************************************************************/
void ctobssim::simulate_background(GCTAObservation* obs,
const GModels& models,
GRan& ran,
GLog* wrklog)
{
// Continue only if observation pointer is valid
if (obs != NULL) {
// If no logger is specified then use the default logger
if (wrklog == NULL) {
wrklog = &log;
}
// Get pointer on event list (circumvent const correctness)
GCTAEventList* events =
static_cast<GCTAEventList*>(const_cast<GEvents*>(obs->events()));
// Loop over all models
for (int i = 0; i < models.size(); ++i) {
// Get data model (NULL if not a data model)
const GModelData* model =
dynamic_cast<const GModelData*>(models[i]);
// If we have a data model that applies to the present observation
// then simulate events
if (model != NULL &&
model->is_valid(obs->instrument(), obs->id())) {
// Get simulated CTA event list. Note that this method
// includes the deadtime correction.
GCTAEventList* list =
dynamic_cast<GCTAEventList*>(model->mc(*obs, ran));
// Continue only if we got a CTA event list
if (list != NULL) {
// Reserves space for events
events->reserve(list->size()+events->size());
// Append events
for (int k = 0; k < list->size(); k++) {
// Get event pointer
GCTAEventAtom* event = (*list)[k];
// Use event only if it falls within ROI
if (events->roi().contains(*event)) {
// Set event identifier
event->event_id(m_event_id);
m_event_id++;
// Append event
events->append(*event);
} // endif: event was within ROI
} // endfor: looped over all events
// Dump simulation results
if (logNormal()) {
*wrklog << gammalib::parformat("MC background events");
*wrklog << list->size() << std::endl;
}
// Free event list
delete list;
} // endif: we had a CTA event list
} // endif: model was valid
} // endfor: looped over all models
} // endif: observation pointer was valid
// Return
return;
}
/***********************************************************************//**
* @brief Simulate source events from photon list
*
* @param[in] obs Pointer on CTA observation.
* @param[in] models Model list.
* @param[in] ran Random number generator.
* @param[in] wrklog Pointer to logger.
*
* Simulate source events from a photon list for a given CTA observation.
* The events are stored in as event list in the observation.
*
* This method does nothing if the observation pointer is NULL. It also
* verifies if the observation has a valid pointing and response.
***************************************************************************/
void ctobssim::simulate_source(GCTAObservation* obs, const GModels& models,
GRan& ran, GLog* wrklog)
{
// Continue only if observation pointer is valid
if (obs != NULL) {
// If no logger is specified then use the default logger
if (wrklog == NULL) {
wrklog = &log;
}
// Get pointer on CTA response. Throw an exception if the response
// is not defined.
const GCTAResponse& rsp = obs->response();
// Make sure that the observation holds a CTA event list. If this
// is not the case then allocate and attach a CTA event list now.
if (dynamic_cast<const GCTAEventList*>(obs->events()) == NULL) {
set_list(obs);
}
// Get pointer on event list (circumvent const correctness)
GCTAEventList* events = static_cast<GCTAEventList*>(const_cast<GEvents*>(obs->events()));
// Extract simulation region.
GSkyDir dir = events->roi().centre().dir();
double rad = events->roi().radius() + g_roi_margin;
// Dump simulation cone information
if (logNormal()) {
*wrklog << gammalib::parformat("Simulation area");
*wrklog << m_area << " cm2" << std::endl;
*wrklog << gammalib::parformat("Simulation cone");
*wrklog << "RA=" << dir.ra_deg() << " deg";
*wrklog << ", Dec=" << dir.dec_deg() << " deg";
*wrklog << ", r=" << rad << " deg" << std::endl;
}
// Initialise indentation for logging
int indent = 0;
// Loop over all Good Time Intervals
for (int it = 0; it < events->gti().size(); ++it) {
// Extract time interval
GTime tmin = events->gti().tstart(it);
GTime tmax = events->gti().tstop(it);
// Dump time interval
if (logNormal()) {
if (events->gti().size() > 1) {
indent++;
wrklog->indent(indent);
}
*wrklog << gammalib::parformat("Time interval", indent);
*wrklog << tmin.convert(m_cta_ref);
*wrklog << " - ";
*wrklog << tmax.convert(m_cta_ref);
*wrklog << " s" << std::endl;
}
// Loop over all energy boundaries
for (int ie = 0; ie < events->ebounds().size(); ++ie) {
// Extract energy boundaries
GEnergy emin = events->ebounds().emin(ie);
GEnergy emax = events->ebounds().emax(ie);
// Dump energy range
if (logNormal()) {
if (events->ebounds().size() > 1) {
indent++;
wrklog->indent(indent);
}
*wrklog << gammalib::parformat("Energy range", indent);
*wrklog << emin << " - " << emax << std::endl;
}
// Loop over all sky models
for (int i = 0; i < models.size(); ++i) {
// Get sky model (NULL if not a sky model)
const GModelSky* model =
dynamic_cast<const GModelSky*>(models[i]);
// If we have a sky model that applies to the present
// observation then simulate events
if (model != NULL &&
model->is_valid(obs->instrument(), obs->id())) {
// Determine duration of a time slice by limiting the
// number of simulated photons to m_max_photons.
// The photon rate is estimated from the model flux
// and used to set the duration of the time slice.
double flux = model->spectral()->flux(emin, emax);
double rate = flux * m_area;
double duration = 1800.0; // default: 1800 sec
if (rate > 0.0) {
duration = m_max_photons / rate;
if (duration < 1.0) { // not <1 sec
duration = 1.0;
}
else if (duration > 180000.0) { // not >50 hr
duration = 180000.0;
}
}
GTime tslice(duration, "sec");
// To reduce memory requirements we split long time
// intervals into several slices.
GTime tstart = tmin;
GTime tstop = tstart + tslice;
// Initialise cumulative photon counters
int nphotons = 0;
// Loop over time slices
while (tstart < tmax) {
// Make sure that tstop <= tmax
if (tstop > tmax) {
tstop = tmax;
}
// Dump time slice
if (logExplicit()) {
if (tmax - tmin > tslice) {
indent++;
wrklog->indent(indent);
}
*wrklog << gammalib::parformat("Time slice", indent);
*wrklog << tstart.convert(m_cta_ref);
*wrklog << " - ";
*wrklog << tstop.convert(m_cta_ref);
*wrklog << " s" << std::endl;
}
// Get photons
GPhotons photons = model->mc(m_area, dir, rad,
emin, emax,
tstart, tstop, ran);
// Dump number of simulated photons
if (logExplicit()) {
*wrklog << gammalib::parformat("MC source photons/slice", indent);
*wrklog << photons.size();
if (model->name().length() > 0) {
*wrklog << " [" << model->name() << "]";
}
*wrklog << std::endl;
}
// Simulate events from photons
for (int i = 0; i < photons.size(); ++i) {
// Increment photon counter
nphotons++;
// Simulate event. Note that this method
// includes the deadtime correction.
GCTAEventAtom* event = rsp.mc(m_area,
photons[i],
*obs,
ran);
if (event != NULL) {
// Use event only if it falls within ROI
if (events->roi().contains(*event)) {
event->event_id(m_event_id);
events->append(*event);
m_event_id++;
}
delete event;
}
} // endfor: looped over events
// Go to next time slice
tstart = tstop;
tstop = tstart + tslice;
// Reset indentation
if (logExplicit()) {
if (tmax - tmin > tslice) {
indent--;
wrklog->indent(indent);
}
}
} // endwhile: looped over time slices
// Dump simulation results
if (logNormal()) {
*wrklog << gammalib::parformat("MC source photons", indent);
*wrklog << nphotons;
if (model->name().length() > 0) {
*wrklog << " [" << model->name() << "]";
}
*wrklog << std::endl;
*wrklog << gammalib::parformat("MC source events", indent);
*wrklog << events->size();
if (model->name().length() > 0) {
*wrklog << " [" << model->name() << "]";
}
*wrklog << std::endl;
}
} // endif: model was a sky model
} // endfor: looped over models
// Dump simulation results
if (logNormal()) {
*wrklog << gammalib::parformat("MC source events", indent);
*wrklog << events->size();
*wrklog << " (all source models)";
*wrklog << std::endl;
}
// Reset indentation
if (logNormal()) {
if (events->ebounds().size() > 1) {
indent--;
wrklog->indent(indent);
}
}
} // endfor: looped over all energy boundaries
// Reset indentation
if (logNormal()) {
if (events->gti().size() > 1) {
indent--;
wrklog->indent(indent);
}
}
} // endfor: looped over all time intervals
// Reset indentation
wrklog->indent(0);
} // endif: observation pointer was valid
// Return
return;
}
/***********************************************************************//**
* @brief Return simulated list of events
*
* @param[in] obs Observation.
* @param[in] ran Random number generator.
* @return Pointer to list of simulated events (needs to be de-allocated by
* client)
*
* @exception GException::invalid_argument
* Specified observation is not a CTA observation.
*
* Draws a sample of events from the background model using a Monte
* Carlo simulation. The region of interest, the energy boundaries and the
* good time interval for the sampling will be extracted from the observation
* argument that is passed to the method. The method also requires a random
* number generator of type GRan which is passed by reference, hence the
* state of the random number generator will be changed by the method.
*
* The method also applies a deadtime correction using a Monte Carlo process,
* taking into account temporal deadtime variations. For this purpose, the
* method makes use of the time dependent GObservation::deadc method.
*
* For each event in the returned event list, the sky direction, the nominal
* coordinates (DETX and DETY), the energy and the time will be set.
***************************************************************************/
GCTAEventList* GCTAModelAeffBackground::mc(const GObservation& obs,
GRan& ran) const
{
// Initialise new event list
GCTAEventList* list = new GCTAEventList;
// Continue only if model is valid)
if (valid_model()) {
// Retrieve CTA observation
const GCTAObservation* cta = dynamic_cast<const GCTAObservation*>(&obs);
if (cta == NULL) {
std::string msg = "Specified observation is not a CTA "
"observation.\n" + obs.print();
throw GException::invalid_argument(G_MC, msg);
}
// Get pointer on CTA IRF response
const GCTAResponseIrf* rsp =
dynamic_cast<const GCTAResponseIrf*>(cta->response());
if (rsp == NULL) {
std::string msg = "Specified observation does not contain"
" an IRF response.\n" + obs.print();
throw GException::invalid_argument(G_MC, msg);
}
// Retrieve CTA response and pointing
const GCTAPointing& pnt = cta->pointing();
// Get pointer to CTA effective area
const GCTAAeff* aeff = rsp->aeff();
if (aeff == NULL) {
std::string msg = "Specified observation contains no effective area"
" information.\n" + obs.print();
throw GException::invalid_argument(G_MC, msg);
}
// Retrieve event list to access the ROI, energy boundaries and GTIs
const GCTAEventList* events =
dynamic_cast<const GCTAEventList*>(obs.events());
if (events == NULL) {
std::string msg = "No CTA event list found in observation.\n" +
obs.print();
throw GException::invalid_argument(G_MC, msg);
}
// Get simulation region
const GCTARoi& roi = events->roi();
const GEbounds& ebounds = events->ebounds();
const GGti& gti = events->gti();
// Get maximum offset value for simulations
double max_theta = pnt.dir().dist(roi.centre().dir()) +
roi.radius() * gammalib::deg2rad;
double cos_max_theta = std::cos(max_theta);
// Set simulation region for result event list
list->roi(roi);
list->ebounds(ebounds);
list->gti(gti);
// Set up spectral model to draw random energies from. Here we use
// a fixed energy sampling for an instance of GModelSpectralNodes.
// This is analogous to to the GCTAModelIrfBackground::mc method.
// We make sure that only non-negative nodes get appended.
GEbounds spectral_ebounds =
GEbounds(m_n_mc_energies, ebounds.emin(), ebounds.emax(), true);
GModelSpectralNodes spectral;
for (int i = 0; i < spectral_ebounds.size(); ++i) {
GEnergy energy = spectral_ebounds.elogmean(i);
double intensity = aeff_integral(obs, energy.log10TeV());
double norm = m_spectral->eval(energy, events->tstart());
double arg = norm * intensity;
if (arg > 0.0) {
spectral.append(energy, arg);
}
}
// Loop over all energy bins
for (int ieng = 0; ieng < ebounds.size(); ++ieng) {
// Compute the background rate in model within the energy
// boundaries from spectral component (units: cts/s).
// Note that the time here is ontime. Deadtime correction will
// be done later.
double rate = spectral.flux(ebounds.emin(ieng), ebounds.emax(ieng));
// Debug option: dump rate
#if defined(G_DUMP_MC)
std::cout << "GCTAModelAeffBackground::mc(\"" << name() << "\": ";
std::cout << "rate=" << rate << " cts/s)" << std::endl;
#endif
// If the rate is not positive then skip this energy bins
if (rate <= 0.0) {
continue;
}
// Loop over all good time intervals
for (int itime = 0; itime < gti.size(); ++itime) {
// Get Monte Carlo event arrival times from temporal model
GTimes times = m_temporal->mc(rate,
gti.tstart(itime),
gti.tstop(itime),
ran);
// Get number of events
int n_events = times.size();
// Reserve space for events
if (n_events > 0) {
list->reserve(n_events);
}
// Debug option: provide number of times and initialize
// statisics
#if defined(G_DUMP_MC)
std::cout << " Interval " << itime;
std::cout << " times=" << n_events << std::endl;
int n_killed_by_deadtime = 0;
int n_killed_by_roi = 0;
#endif
// Loop over events
for (int i = 0; i < n_events; ++i) {
// Apply deadtime correction
double deadc = obs.deadc(times[i]);
if (deadc < 1.0) {
if (ran.uniform() > deadc) {
#if defined(G_DUMP_MC)
n_killed_by_deadtime++;
#endif
continue;
}
}
// Get Monte Carlo event energy from spectral model
GEnergy energy = spectral.mc(ebounds.emin(ieng),
ebounds.emax(ieng),
times[i],
ran);
// Get maximum effective area for rejection method
double max_aeff = aeff->max(energy.log10TeV(), pnt.zenith(),
pnt.azimuth(), false);
// Skip event if the maximum effective area is not positive
if (max_aeff <= 0.0) {
continue;
}
// Initialise randomised coordinates
double offset = 0.0;
double phi = 0.0;
// Initialise acceptance fraction and counter of zeros for
// rejection method
double acceptance_fraction = 0.0;
int zeros = 0;
// Start rejection method loop
do {
// Throw random offset and azimuth angle in
// considered range
offset = std::acos(1.0 - ran.uniform() *
(1.0 - cos_max_theta));
phi = ran.uniform() * gammalib::twopi;
// Compute function value at this offset angle
double value = (*aeff)(energy.log10TeV(), offset, phi,
pnt.zenith(), pnt.azimuth(),
false);
// If the value is not positive then increment the
// zeros counter and fall through. The counter assures
// that this loop does not lock up.
if (value <= 0.0) {
zeros++;
continue;
}
// Value is non-zero so reset the zeros counter
zeros = 0;
// Compute acceptance fraction
acceptance_fraction = value / max_aeff;
} while ((ran.uniform() > acceptance_fraction) &&
(zeros < 1000));
// If the zeros counter is non-zero then the loop was
// exited due to exhaustion and the event is skipped
if (zeros > 0) {
continue;
}
// Convert CTA pointing direction in instrument system
GCTAInstDir mc_dir(pnt.dir());
// Rotate pointing direction by offset and azimuth angle
mc_dir.dir().rotate_deg(phi * gammalib::rad2deg,
offset * gammalib::rad2deg);
// Compute DETX and DETY coordinates
double detx(0.0);
double dety(0.0);
if (offset > 0.0 ) {
detx = offset * std::cos(phi);
dety = offset * std::sin(phi);
}
// Set DETX and DETY coordinates
mc_dir.detx(detx);
mc_dir.dety(dety);
// Allocate event
GCTAEventAtom event;
// Set event attributes
event.dir(mc_dir);
event.energy(energy);
event.time(times[i]);
// Append event to list if it falls in ROI
if (events->roi().contains(event)) {
list->append(event);
}
#if defined(G_DUMP_MC)
else {
n_killed_by_roi++;
}
#endif
} // endfor: looped over all events
// Debug option: provide statisics
#if defined(G_DUMP_MC)
std::cout << " Killed by deadtime=";
std::cout << n_killed_by_deadtime << std::endl;
std::cout << " Killed by ROI=";
std::cout << n_killed_by_roi << std::endl;
#endif
} // endfor: looped over all GTIs
} // endfor: looped over all energy boundaries
} // endif: model was valid
// Return
return list;
}
/***********************************************************************//**
* @brief Return simulated list of events
*
* @param[in] obs Observation.
* @param[in] ran Random number generator.
* @return Pointer to list of simulated events (needs to be de-allocated by
* client)
*
* @exception GException::invalid_argument
* Specified observation is not a CTA observation.
*
* Draws a sample of events from the background model using a Monte
* Carlo simulation. The region of interest, the energy boundaries and the
* good time interval for the sampling will be extracted from the observation
* argument that is passed to the method. The method also requires a random
* number generator of type GRan which is passed by reference, hence the
* state of the random number generator will be changed by the method.
*
* The method also applies a deadtime correction using a Monte Carlo process,
* taking into account temporal deadtime variations. For this purpose, the
* method makes use of the time dependent GObservation::deadc method.
*
* For each event in the returned event list, the sky direction, the nominal
* coordinates (DETX and DETY), the energy and the time will be set.
***************************************************************************/
GCTAEventList* GCTAModelIrfBackground::mc(const GObservation& obs, GRan& ran) const
{
// Initialise new event list
GCTAEventList* list = new GCTAEventList;
// Continue only if model is valid)
if (valid_model()) {
// Retrieve CTA observation
const GCTAObservation* cta = dynamic_cast<const GCTAObservation*>(&obs);
if (cta == NULL) {
std::string msg = "Specified observation is not a CTA observation.\n" +
obs.print();
throw GException::invalid_argument(G_MC, msg);
}
// Get pointer on CTA IRF response
const GCTAResponseIrf* rsp = dynamic_cast<const GCTAResponseIrf*>(cta->response());
if (rsp == NULL) {
std::string msg = "Specified observation does not contain"
" an IRF response.\n" + obs.print();
throw GException::invalid_argument(G_MC, msg);
}
// Retrieve CTA response and pointing
const GCTAPointing& pnt = cta->pointing();
// Get pointer to CTA background
const GCTABackground* bgd = rsp->background();
if (bgd == NULL) {
std::string msg = "Specified observation contains no background"
" information.\n" + obs.print();
throw GException::invalid_argument(G_MC, msg);
}
// Retrieve event list to access the ROI, energy boundaries and GTIs
const GCTAEventList* events = dynamic_cast<const GCTAEventList*>(obs.events());
if (events == NULL) {
std::string msg = "No CTA event list found in observation.\n" +
obs.print();
throw GException::invalid_argument(G_MC, msg);
}
// Get simulation region
const GCTARoi& roi = events->roi();
const GEbounds& ebounds = events->ebounds();
const GGti& gti = events->gti();
// Set simulation region for result event list
list->roi(roi);
list->ebounds(ebounds);
list->gti(gti);
// Create a spectral model that combines the information from the
// background information and the spectrum provided by the model
GModelSpectralNodes spectral(bgd->spectrum());
for (int i = 0; i < spectral.nodes(); ++i) {
GEnergy energy = spectral.energy(i);
double intensity = spectral.intensity(i);
double norm = m_spectral->eval(energy, events->tstart());
spectral.intensity(i, norm*intensity);
}
// Loop over all energy boundaries
for (int ieng = 0; ieng < ebounds.size(); ++ieng) {
// Compute the background rate in model within the energy
// boundaries from spectral component (units: cts/s).
// Note that the time here is ontime. Deadtime correction will
// be done later.
double rate = spectral.flux(ebounds.emin(ieng), ebounds.emax(ieng));
// Debug option: dump rate
#if defined(G_DUMP_MC)
std::cout << "GCTAModelIrfBackground::mc(\"" << name() << "\": ";
std::cout << "rate=" << rate << " cts/s)" << std::endl;
#endif
// Loop over all good time intervals
for (int itime = 0; itime < gti.size(); ++itime) {
// Get Monte Carlo event arrival times from temporal model
GTimes times = m_temporal->mc(rate,
gti.tstart(itime),
gti.tstop(itime),
ran);
// Get number of events
int n_events = times.size();
// Reserve space for events
if (n_events > 0) {
list->reserve(n_events);
}
// Debug option: provide number of times and initialize
// statisics
#if defined(G_DUMP_MC)
std::cout << " Interval " << itime;
std::cout << " times=" << n_events << std::endl;
int n_killed_by_deadtime = 0;
int n_killed_by_roi = 0;
#endif
// Loop over events
for (int i = 0; i < n_events; ++i) {
// Apply deadtime correction
double deadc = obs.deadc(times[i]);
if (deadc < 1.0) {
if (ran.uniform() > deadc) {
#if defined(G_DUMP_MC)
n_killed_by_deadtime++;
#endif
continue;
}
}
// Get Monte Carlo event energy from spectral model
GEnergy energy = spectral.mc(ebounds.emin(ieng),
ebounds.emax(ieng),
times[i],
ran);
// Get Monte Carlo event direction from spatial model.
// This only will set the DETX and DETY coordinates.
GCTAInstDir instdir = bgd->mc(energy, times[i], ran);
// Derive sky direction from instrument coordinates
GSkyDir skydir = pnt.skydir(instdir);
// Set sky direction in GCTAInstDir object
instdir.dir(skydir);
// Allocate event
GCTAEventAtom event;
// Set event attributes
event.dir(instdir);
event.energy(energy);
event.time(times[i]);
// Append event to list if it falls in ROI
if (events->roi().contains(event)) {
list->append(event);
}
#if defined(G_DUMP_MC)
else {
n_killed_by_roi++;
}
#endif
} // endfor: looped over all events
// Debug option: provide statisics
#if defined(G_DUMP_MC)
std::cout << " Killed by deadtime=";
std::cout << n_killed_by_deadtime << std::endl;
std::cout << " Killed by ROI=";
std::cout << n_killed_by_roi << std::endl;
#endif
} // endfor: looped over all GTIs
} // endfor: looped over all energy boundaries
} // endif: model was valid
// Return
return list;
}