OPERA tau neutrino candidate event 12227007334, OPERA collaboration
Cite as: OPERA collaboration (2018). OPERA tau neutrino candidate event 12227007334. CERN Open Data Portal. DOI:10.7483/OPENDATA.OPERA.NRED.999W
Dataset Derived OPERA CERN-SPS
This neutrino candidate occurred on August $14^{th}$ 2012 in the second super-module, in the $24^{th}$ wall, 7 brick walls upstream of the spectrometer. No muon track was reconstructed by the electronic detectors and the event was classified as ${0\mu}$. The activity in the Target Trackers was limited to the 8 walls downstream of the vertex brick. The interaction was fully reconstructed in the brick, looking for tracks within an angular acceptance defined by $\tan \vartheta = 3$. The visible energy of the event was measured to be ${(12\pm 4)}$~GeV.
In the analysis of the interface emulsion films, 15 tracks were detected, six of which showed a converging path, thus validating the brick extraction and development. By following back these tracks with the scan-back procedure, the neutrino interaction was located between the $15^{th}$ and $16^{th}$ emulsion films, 42 plates from the downstream face of the brick. Its vertex consisted of two charged tracks, one of which exhibits a kink topology with ${\theta_{kink}=(90\pm 2)}$~mrad, after a flight length of ${(960 \pm 30)}$~${\mu}$m. The distance of closest approach between the ${\tau}$ candidate and the other primary track is 0.1~${\mu}$m.
In addition to these two tracks, four forward-going and two backward-going nuclear fragments pointing to the primary vertex were observed.
The ${\tau}$ daughter interacted after having crossed 22 plates, producing four charged particles and a photon, and it could thus be unambiguously identified as a hadron. Its measured momentum is ${11.0^{+13.9}_{-3.9}}$~GeV/c, while its impact parameter w.r.t.~the primary vertex is ${(83 \pm 5)}$~${\mu}$m.
The second primary track measured momentum is ${(1.1\pm 0.2)}$~GeV/c and it was classified as a proton from its energy loss in the emulsion target. The linear density of grains along the track left by a particle, indeed, is correlated with its energy loss. The ratio between the grain density of this track and that of the ${\tau}$ daughter track is ${(1.45 \pm 0.06)}$, to be compared with ${(1.38 \pm 0.14)}$ expected for a proton/m.i.p.~ratio. Therefore, the second primary track was likely produced by a proton.
This event was thus interpreted as a $\nu_{\tau}$ charged-current interaction with the $z\tau$ lepton decaying into a single hadron. A detailed description of the event is given in 10.1103/PhysRevLett.115.121802.
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.