OPERA tau neutrino candidate event 10123059807, OPERA collaboration
Cite as: OPERA collaboration (2018). OPERA tau neutrino candidate event 10123059807. CERN Open Data Portal. DOI:10.7483/OPENDATA.OPERA.FF4D.MNC9
Dataset Derived OPERA CERN-SPS
This ${\nu_\tau}$ interaction occurred on May 3$^{rd}$ 2010 in the second super-module, in the 27$^{th}$ wall, 4 walls upstream of the muon spectrometer, well inside the target. 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, 4 tracks were found showing a converging path. This finding triggered the brick film development. By the scan-back procedure, the neutrino interaction was located with 7 tracks were reconstructed. The neutrino interaction vertex was located in the lead between the $19^{th}$ and $20^{th}$ emulsion films. One backward track was found in films 18-19 and a black segment in film 20. No $\gamma$ was detected. All tracks were identified as hadrons using their overall track length reconstructed along their path, the topology at their end-point and the correlation between their momentum and range.
It turned out that the 7 tracks did not originate from the same vertex because their impact parameters exceed the values expected according to the resolution: therefore, a particle decay must have occurred over a short flight length since it happened in the same lead plate. Looking at the impact parameters of the tracks, two hypotheses were made on the event topology: a primary vertex with 4 tracks and a trident decay or a primary vertex composed by 3 tracks and a secondary vertex with 4 tracks attached. Other hypotheses were discarded given their probability lower than $0.01\%$. The most probable hypothesis is the first one, with a vertex topological probability of $72.3\%$, according to the impact parameters, and corresponds to a $\nu_{\tau}$ charged-current interaction with the $\tau$ lepton decaying into three hadrons. In this configuration, the kink angle, evaluated as the mean kink angle for each daughter track, is 231~mrad. The hypothesis of a short decay of a heavy particle is supported also by the invariant mass measurement done with the three daughter tracks, 1.2~GeV, assuming the ${\pi}$ mass for all daughters.
The rejected hypothesis could be explained only by a $\nu_\mu$ charged-current interaction with charmed hadron production that would require the presence of a muon at the primary vertex, strongly suppressed by the hadron identification of the tracks.
The neutrino energy was measured to be $16.4$~GeV/c. This event was thus interpreted as a $\nu_{\tau}$ charged-current interaction with the $\tau$ lepton decaying into three hadrons.
Electronic detector data for tau neutrino appearance studies
This event is part of OPERA Emulsion Detector tau appearance datasetVariable | 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 |
Demobbed-viewer is a JavaScript application developed for the CERN Open Data Portal. The application is supposed to visualise neutrino interaction events registered in the OPERA experiment.
At present OPERA open data sample includes four sub-samples (a sub-sample to display can be specified in the left part of the toolbar):
- the "nuTau" sub-sample (Electronic detector data + Emulsion data) includes 10 tau neutrino candidate events observed by OPERA in the CNGS neutrino beam.
- the "nuMu" sub-sample (Electronic detector data + Emulsion data) includes 817 events used in the study of charged hadron multiplicities in charged-current neutrino-lead interactions in the OPERA detector.
- the "nuE" sub-sample (Electronic detector data + Emulsion data) includes 19 electron neutrino candidate events registered in the OPERA detector.
- the "charm" sub-sample (Electronic detector data + Emulsion data) includes 50 charm decay candidate events registered in the OPERA detector.
Opera hybrid experimental setup (described in detail here) included Electronic detectors (ED) for real-time detection of neutrino interactions and nuclear emulsions for precision analysis of neutrino event topologies. The ED provided positions of hits in two perpendicular planes: XZ (top view) and YZ (side view). By default, only ED information is displayed in the Demobbed-viewer. After analysis of the ED data the unit of OPERA target (lead-emulsion or ECC brick) that most probably contained the neutrino interaction vertex was extracted from the detector and its emulsion data were analysed as well. 3D view of reconstructed emulsion data can be opened in the ECC display (see description below).
Brief description of available button actions:
/ - go to the previous/next event (if any) in the selected sub-sample. Also the event Id can be specified directly in the nearest edit box.
- reload the currently displayed event.
/ - zoom in/out. Please note that the default (whole detector) views of the ED display can't be zoomed out.
- move the XZ and YZ camera views to the vertex brick. ECC brick that contains the primary neutrino interaction vertex will be shown (an appropriate zooming will be adjusted automatically). The vertex position as well as projections of muon and some long hadron tracks found in the emulsion will be displayed as well.
- move the XZ and YZ camera views and adjust zooming in order to display the whole neutrino event region.
- show the whole detector region (default option).
, , , and - move the ED display camera views, correspondingly, up, down, left, and right.
The ECC display view can be rotated or moved with help of the left or right mouse buttons, correspondingly.
, , or - show the default XZ, YZ, or XY view of the event in the ECC display.
/ - stretch/compress the ECC view in the vertical (Y) direction.
- start/accelerate animated rotation of the ECC event around the Y (vertical) axis. This button can be clicked several (but not so many!) times.
- decelerate animated rotation of the ECC event. In order to stop the rotation this button has to be clicked the same number of times as the "accelerating" button has been clicked before.
A browser-based event display for visualisation of open data of the OPERA experiment.
This application uses d3.js and three.js libraries. The code is available on the GitHub repository.
Contributors: S. Dmitrievsky (JINR, Dubna, Russia), G. Tsanaktsidis (CERN, Geneva, Switzerland), M. Vidal (CERN, Geneva, Switzerland).
These OPERA event data files can be visualised using the online OPERA event display
The open data are released under the Creative Commons CC0 waiver. Neither the experiment(s) ( OPERA ) nor CERN endorse any works, scientific or otherwise, produced using these data. All releases will have a unique DOI that you are requested to cite in any applications or publications.