OPERA tau neutrino candidate event 9190097972

Description

This ${\nu_\tau}$ interaction occurred on July 9$^{th}$ 2009 in the first super-module, in the $25^{th}$ wall. 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 $\tan\theta=3$.

After the analysis of the interface emulsion films, 5 tracks were found showing a converging path. This finding triggered the brick film development. By the scan-back procedure, the neutrino interaction was located in the lead layer between the $35^{st}$ and $36^{nd}$ emulsion films.

The neutrino interaction vertex consists of five charged tracks. From the analysis of their impact parameters, it turned out that all tracks could not originate from the same vertex: a short decay must have occurred. Looking at the impact parameters, one of the tracks must have originated from a decay vertex occurred 10~$\mu$m upstream from the downstream face of the lead plate that contains the neutrino vertex. Since both primary and decay vertices are in the same lead plate, there are no base-tracks in emulsion associated to the $\tau$ lepton.

The flight length has been evaluated to be 822~$\mu$m, while the kink angle 146~mrad. All tracks were recognized as hadrons: two of them stopped inside the brick, the others were classified thanks to the correlation between their momentum and range. The neutrino energy was measured to be $9.6$~GeV.

This event was thus interpreted as a $\nu_{\tau}$ charged-current interaction with the $\tau$ lepton decaying into a single hadron.

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. 10.3 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 9190097972

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