Dorothea

From ancient Greek, Δωροθέα: gift of God.

The purpose of Dorothea is to process the PMaps (output of Irene) and reconstruct point-like events. Therefore, all the information included in the S2 peaks is collapsed into a single x, y, z point with summarized S1 and S2 properties. Additionally, some parameters regarding the S1 and S2 peaks are provided as a tool for further selections. Last, it is worth noting that for events where more than one S1 or S2 (or both) are present in the event, a point is reconstructed for each possible combination.

Input

• /Run/events

• /Run/runInfo

• /PMAPS/S1

• /PMAPS/S1Pmt

• /PMAPS/S2

• /PMAPS/S2Pmt

• /PMAPS/S2Si

Output

• /DST/Events: summary of the reconstructed events and their main properties. Each row represents one combination of an S1 and a S2 identified under the same event but with its corresponding s1_peak and s2_peak identifier. The full list and description of the parameters in the table can be found here.

• /Filters/s12_selector: flag for whether an event passed the S1 and S2 selections

Config

Besides the Common arguments to every city, Dorothea has the following arguments:

Parameter	Type	Description
drift_v	float	Drift velocity of the secondary electrons towards the anode.
s1|s2_nmin|nmax	int	Lower/upper limits to the number of S1/S2 peaks per event.
s1|s2_emin|emax	float	Lower/upper limits to the energy (integral under the peak) of each S1/S2 peak (pes).
s1|s2_wmin|wmax	float	Lower/upper limits to the width (time over threshold) of each S1/S2 peak.
s1|s2_hmin|hmax	float	Lower/upper limits to the height (maximum amplitude) of each S1/S2 peak (pes).
s1|s2_ethr	float	Threshold for each bin within each S1/S2 to be considered for the energy computation (pes).
s2_nsipmmin|nsipmmax	int	Lower/upper limits to the number of SiPM sensors with a recorded signal.
global_reco_params	dict	Set of parameters for the corona algorithm. Since the desired one is the barycenter reconstruction, the only required elements in the dictionary are: Qthr: time-integrated charge threshold, ignore all SiPMs with less than Qthr pes. lm_radius=-1: sets the algorithm to be the barycenter.

Workflow

The workflow for Dorothea starts with a filter that removes the peaks not satisfying the limits provided via configuration file. The event is selected if and only if the number of remaining peaks falls in the range [s1_nmin, s1_nmax] and [s2_nmin, s2_nmax]. Then, it proceeds to perform the point-like reconstruction. This algorithm collapses the whole S2 information into a single point, which has summarized information about S1 and S2, such as:

• The x and y position are determined via a charge-weighted average (a.k.a. center of gravity or barycenter). This makes use of the so-called corona algorithm, with the proper configuration to apply the barycenter computation.

• The z coordinate is derived from the time difference between the maximum amplitude of the S1 and S2 considered, corrected by the drift velocity.

• The energy is the integral under the PMT S2 peak using the bins above the threshold.

• The charge is the integral under the SiPM S2 peak. A previous threshold has already been applied in the Irene city.

Output table

The output table contains a set of peak features:

Parameter	Type	Description
event	int	Event ID. As an event can have several S1 and S2 combinations, each one representing one row, this number identifies all the reconstructed points within the same original waveform.
time	float	Timestamp of the event.
s1_peak	int	S1 ID. It identifies the S1 within an event.
s2_peak	int	S2 ID. It identifies the S2 within an event.
nS1	int	Number of S1 present in the event.
nS2	int	Number of S2 present in the event.
S1w	float	S1 time over threshold (ns).
s1h	float	S1 maximum amplitude (pes).
S1e	float	S1 PMT- and time-summed amplitude over threshold (pes).
S1t	float	Waveform time at maximum S1 amplitude (ns).
S2w	float	S2 time over threshold (mus).
s2h	float	S2 maximum amplitude (pes).
S2e	float	S2 PMT- and time-summed amplitude over threshold (pes).
S2t	float	Waveform time at maximum S2 amplitude (ns).
S2q	float	S2 SiPM- and time-summed amplitude over threshold (pes).
Nsipm	int	Number of SiPMs with signal over threshold.
DT	float	Drift Time —i.e., time difference between the corresponding S1 and S2— (\(\mu s\)).
Z	float	Reconstructed z position coordinate —i.e., the DT times the drift velocity— (mm).
Zrms	float	Standard deviation of the PMT signal in the z coordinate (mm).
X	float	Reconstructed x position coordinate using the barycenter algorithm (mm).
Y	float	Reconstructed y position coordinate using the barycenter algorithm (mm).
R	float	Reconstructed radial coordinate, \(r^2=x^2+y^2\) (mm).
Phi	float	Reconstructed azimuthal coordinate, \(\phi=\arctan(y/x)\) (rad).
Xrms	float	Standard deviation of the PMT signal in the x coordinate (mm).
Yrms	float	Standard deviation of the PMT signal in the y coordinate (mm).

As a final remark, notice that the peak height, width, time and energy come from the PMTs, while the charge (S2q) and the xy position come from the SiPMs.