OPERA tau neutrino candidate event 11143018505

Description

This neutrino interaction occurred on May $23^{rd}$ 2011 in the first super-module, 19 brick walls downstream of the spectrometer. No muon was identified by the reconstruction of the data provided by electronic detectors. All tracks possibly related to the interaction were searched for in the brick within an angular acceptance defined by $\tan\vartheta=3$.

After the analysis of interface emulsion films, 27 trigger tracks were identified and they showed a clear converging pattern; out of them 11 were found also in the brick. Several of them are clustered in a few hundreds microns area, this is an indication of electromagnetic activity related to the primary neutrino interaction. After the analysis of interface emulsion films, 27 trigger tracks were identified and they showed a clear converging pattern; out of them 11 were found also in the brick. Several of them are clustered in a few hundreds microns area, this is an indication of electromagnetic activity related to the primary neutrino interaction.

The peculiarity of this event is that it has two secondary vertices within about 1~mm from the primary one.

The neutrino vertex is defined by 3 tracks. Of the two secondary vertices, one has 2-prongs and occurs in the same lead plate of the neutrino vertex, after a flight length of $103$~$\mu$m, while the other one exhibits a kink after a flight length of $1160$~$\mu$m.

All tracks were classified as hadrons using their overall track length reconstructed along all the downstream available bricks, the topology at their end-point and the correlation between their momentum and range. The energy of the neutrino interaction was measured to be $23.2$~GeV/c.

The most probable interpretation for this event is a $\nu_\tau$ charged-current interaction with charmed hadron production. Other possibilities like a neutral-current $\nu_{\mu}$ interaction with associated charm production were discarded with a good significance using a multivariate analysis method. The most discriminating variables used were the lepton-hadron transverse angle and the daughter momentum. With respect to the non $\tau$-charm hypothesis, the observed event has a very low probability, about $10^{-4}$, which corresponds to a significance of 3.5$\sigma$.

Related datasets

This event is part of OPERA Electronic Detector tau appearance dataset

Electronic detector data for tau neutrino appearance studies

This event is part of OPERA Emulsion Detector tau appearance dataset

Emulsion data for neutrino tau appearance studies

Dataset characteristics

1 events. 14 files. 19.4 kB in total.

Dataset semantics

Variable	Description
amplL	PMT amplitude measured from the "left" side of a scintillator strip (in photo-electrons)
amplR	PMT amplitude measured from the "right" side of a scintillator strip (in photo-electrons)
amplRec	PMT amplitude reconstructed from the "left" and "right" side amplitudes of a scintillator strip taking into account light attenuation in a WLS fiber (in photo-electrons)
clLength	cluster length (in cm)
driftDist	drift distance (in cm)
enHad	energy of a hadron jet (in GeV)
enNeu	energy of a neutrino (in GeV)
enVis	visible energy (in MeV)
evID	event Id (10- or 11-digit number)
globPosX	X position of a vertex in the OPERA detector system of reference (in cm)
globPosY	Y position of a vertex in the OPERA detector system of reference (in cm)
globPosZ	Z position of a vertex in the OPERA detector system of reference (in cm)
muMom	momentum of a muon (in GeV/c)
posX	For Electronic Detector events, X position of a drift tube, RPC, Target Tracker hit in the OPERA detector system of reference (in cm). For Emulsion Detector events, X position of a track/vertex in the OPERA brick system of reference (in micrometers).
posX1	X position of the beginning of a line in the OPERA brick system of reference (in micrometers)
posX2	X position of the end of a line in the OPERA brick system of reference (in micrometers)
posY	For Electronic Detector events, Y position of an RPC hit in the OPERA detector system of reference (in cm). For Emulsion Detector events, Y position of a track/vertex in the OPERA brick system of reference (in micrometers).
posY1	Y position of the beginning of a line in the OPERA brick system of reference (in micrometers)
posY2	Y position of the end of a line in the OPERA brick system of reference (in micrometers)
posZ	For Electronic Detector events, Z position of a drift tube, RPC, Target Tracker hit in the OPERA detector system of reference (in cm). For Emulsion Detector events, Z position of a track/vertex in the OPERA brick system of reference (in micrometers).
posZ1	Z position of the beginning of a line in the OPERA brick system of reference (in micrometers)
posZ2	Z position of the end of a line in the OPERA brick system of reference (in micrometers)
primary	flag of a vertex: 1 - primary vertex; 0 - not primary vertex
slopeXZ	tangent of a track angle in XZ view
slopeYZ	tangent of a track angle in YZ view
timestamp	event time in milliseconds since 01/01/1970
trType	type of a track: 1 - muon; 2 - hadron; 3 - electron/positron; 8 - tau lepton

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Visualise OPERA detector event 11143018505

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