The trigger system of the CHORUS experiment

A new apparatus for detection of $\nu_{\mu} \rightarrow \nu_{\tau}$ oscillation has been successfully constructed and operated by the CHORUS Collaboration for the CERN-WA95 experiment. The design , implementation and performance of the electronic trigger system is described. A trigger efficiency of 99$\%$ was measured for $\nu_{\mu}$ charged current events and 90$\%$ for neutral current e vents

Charged-Particle Multiplicities in Charged-Current Neutrino-- and Anti-Neutrino--Nucleus Interactions

The CHORUS experiment, designed to search for $\nu_{\mu}\to\nu_{\tau}$ oscillations, consists of a nuclear emulsion target and electronic detectors. In this paper, results on the production of charged particles in a small sample of charged-current neutrino-- and anti-neutrino--nucleus interactions at high energy are presented. For each event, the emission angle and the ionization features of the charged particles produced in the interaction are recorded, while the standard kinematic variables are reconstructed using the electronic detectors. The average multiplicities for charged tracks, the pseudo-rapidity distributions, the dispersion in the multiplicity of charged particles and the KNO scaling are studied in different kinematical regions. A study of quasi-elastic topologies performed for the first time in nuclear emulsions is also reported. The results are presented in a form suitable for use in the validation of Monte Carlo generators of neutrino--nucleus interactions.Comment: 17 pages, 5 figure

The data acquisition system of the CHORUS experiment

In the years 1994-1998 the CHORUS Collaboration has recorded data in the CERN WA95 experiment. Here we describe the data acquisition system that has been used, featuring concurrent hierarchical state machines, a remote operating system, a buffer manager, a dispatcher, a control panel and a supervisor

The data acquisition system of the CHORUS experiment

In the years 1994--1998 the CHORUS Collaboration has recorded data in the CERN WA95 experiment. Here we describe the data acquisition system that has been used, featuring concurrent hierarchical state machines, a remote operating system, a buffer manager, a dispatcher, a control panel and a supervisor

Observation of weak neutral current neutrino production of J/ψJ/\psi

Observation of \jpsi production by neutrinos in the calorimeter of the CHORUS detector exposed to the CERN SPS wide-band \numu beam is reported. A spectrum-averaged cross-section $\sigma^{\mathrm{J/\psi}}$ = (6.3 $\pm$ 3.0) $\times \mathrm{10^{-41}~cm^{2}}$ is obtained for 20 GeV $\leq E_{\nu} \leq$ 200 GeV. The data are compared with the theoretical model based on the QCD Z-gluon fusion mechanism

The CHORUS neutrino oscillation search experiment

The CHORUS experiment has successfully finished run I (320~000 recorded \numu\ CC in 94/95) and performed half of run II (225~000 \numu\ CC in 96). The analysis chain was exercised on a small data sample for the muonic \tdecay\ search using for the first time fully automatic emulsion scanning. This pilot analysis, resulting in a limit \sintth \leq 3 \cdot 10^{-2}, confirms that the CHORUS proposal sensitivity (\sintth \leq 3 \cdot 10^{-4}) is within reach in two years

Detection and reconstruction of short-lived particles produced by neutrino interactions in emulsion

In this dissertation, several different topics related to the chorus experiment are pre- sented. The chorus experiment has been used to study neutrino oscillations using the neutrino beam at cern. The neutrino oscillation hypothesis provided an explanation for the lower than expected fluxes of solar and atmospheric neutrinos. There are three neutrino species in nature corresponding to different weak eigenstates, namely, the elec- tron neutrino (νe ), the muon neutrino (νμ ), and the tau neutrino (ντ ). The lower fluxes could be interpreted as spontaneous oscillations between electron and muon neutrinos and between muon and tau neutrinos. The chorus experiment was designed to detect oscillation of muon neutrinos into tau neutrinos with small mixing probability down to 2 · 10−4 and a mass difference square between νμ and ντ larger than 0.5 eV2 . In the last decade, several disappearance experiments have confirmed the neutrino oscillation hypothesis and showed that oscillations occur between mass eigenstates with mass differences of 8 · 10−5 eV2 and 2.5 · 10−3 eV2 . The observed oscillations correspond to almost maximal mixing probability. Current and future efforts focus on detecting the remaining sub-dominant mixing. In the chorus experiment, one looks for the typical decay signature of a τ particle in a large stack of nuclear emulsion plates. Emulsion can record with very high resolution the tracks and decays of short-lived particles, like τ leptons and charmed mesons. A hybrid setup is used consisting of electronic detectors downstream of a 770 kg emulsion target. The electronic detectors consist of an accurate tracking station followed by a hadron spectrometer, a calorimeter, and a muon spectrometer. These detectors are used to measure particle momenta and to select one track per event for scanning the emulsion. Hybrid detectors combined with automated microscopes have greatly increased the amount of emulsion that can be scanned and the information that can be extracted. The fken laboratory in Nagoya developed designated hardware that can find a track with known angle in a 100 μm slice of emulsion. Further upgraded new hardware can find all tracks with slopes within a given angular range. The hardware is used to locate the neutrino vertex by following an electronically measured track from one plate to the next. The new hardware is then used to reconstruct all tracks and vertices of the event. This is done by combining track segments found in the 100 μm upstream layers of the eight plates around the interaction point. The suppression of background in the chorus experiment relies on the measurement of hadron momenta in the hadron spectrometer. A honeycomb drift-tube tracker was added to the detector to improve this measurement. This made it possible to reconstruct independently 3-d track segments in the hadron spectrometer. This improved the uncer- tainty on hadron momenta from ∆p/p = 0.352 + 0.38p/GeV to 0.352 + 0.25p/GeV, where the constant term is due to multiple scattering. The read-out of this detector is based on a continuous sampling of the over–threshold signal of all wires. Because all transitions of a wire’s signal are recorded, both leading edge and pulse length can be recovered. The bit-stream of samples is stored in four phases in separate memory banks. Failure of some memory banks does not destroy the hit information but only lowers its timing accuracy. summary A new automatic emulsion scanning system was developed at cern. For this, new microscope optics with a large field of view were deployed and emulsion scanning was implemented in software. Using software for track finding in emulsion images requires an algorithm capable of handling of the order of 105 3-d hits in a few seconds. An algorithm was developed that searches a network of connected hits. The connection graph links hits in close proximity with a predefined restriction. In this case, the link should possibly be part of a track. This graph is created by sorting the hits in k -dimensional space using a specially designed ordered container with logarithmic search time. The track-finding algorithm considers any connection between two hits as a possible track and builds longer segments using a limited depth-first search of the connection graph. Although originally written for track finding in emulsion, the track-finding algorithm can work in any dimension and is decoupled from the actual hit and track model. The track model and the acceptance of hits in a track are handled by a specific implementation of an abstract acceptance class. The track-finding implementation has been used to find bent tracks in the harp time-projection chamber. In the chorus emulsion application, it has enabled improvements in the vertex location efficiency. It can also be used to reduce human confirmation of secondary vertices by applying it to data taken over the full emulsion thickness. An emulsion-specific algorithm was developed to look for tracks with a known direction. The algorithm is based on moving hits along the track direction and summing the number of hits in its angular acceptance region. Searching for hits in these acceptance regions can be done in logarithmic time using the aforementioned containers. The track-finding algorithm is then used to verify the existence of a track in the small volumes defined by a track-trigger sum over threshold. The k -d space ordering containers have been used throughout the work described in this dissertation, for example in several alignment procedures. The emulsion volume, scanned around the neutrino vertex, defines a decay space for short-lived particles. The maximum decay length is about 4.5 mm along the beam di- rection. In the chorus experiment, 1048 charged-current νμ interactions, identified by a μ− from the primary vertex, with a secondary decay vertex from a D0 meson have been reconstructed. These events were used to study D∗+ resonance production. The decay D∗+ → D0 π + can be identified using the π + momentum measured in the hadron spectrometer and the direction of both the D0 and π + measured in the emulsion. From the observed 22.1 ± 5.5 events, the cross-section ratio for hadronization of a charm quark into D∗+ and D0 is derived: σ (D∗+ ) /σ D0 = 0.38 ± 0.09(stat) ± 0.05(syst). The production cross-section of D∗+ with respect to the total charged-current cross-section is σ (D∗+ ) /σ (CC) = [1.02 ± 0.25(stat) ± 0.15(syst)] %

The impact of buildings and vegetation on air quality. Scanning en scouting air quality

De invloed van bebouwing en vegetatie rond snelwegen op de luchtkwaliteit blijkt gering en in enkele gevallen complex van aard. Gebouwen en vegetatie kunnen van invloed zijn op de luchtkwaliteit van de directe omgeving. De mate waarin is in geval van overschrijdingen van de EU-richtlijnen van belang voor de verantwoordelijke bestuurders. Om meer inzicht te verkrijgen in deze effecten is onderzoek uitgevoerd door het RIVM. In een beperkt complexe situatie rondom een snelweg en een provinciale weg zijn luchtkwaliteitsmetingen voor PM10 en stikstofdioxide uitgevoerd.De invloed van vegetatie kon niet worden aangetoond en wordt voor de onderhavige situatie als zeer gering of afwezig geschat. Nader onderzoek waarbij de structuur van de vegetatie verder wordt geoptimaliseerd kan wellicht uitsluitsel geven over de mogelijk positieve invloed hiervan. De invloed van hoge gebouwen is zeer complex gebleken en kan leiden tot hogere concentraties stikstofdioxide aan de lijzijde van het gebouw. Een belangrijke observatie in het onderzoek is de hoge bijdrage van lokaal verkeer. In het onderhavige onderzoek werd dit duidelijk onderschat en verwacht wordt dat dit vaker plaatsvindt. Hierdoor kan de relatieve invloed van maatregelen gericht tegen de emissies van verkeer op de snelweg worden overschat.The impact on air quality of build-up and vegetation near highways appears to be limited and in same cases rather complex. Buildings and vegetation will have an impact on air quality in the direct surroundings. In case of exceedences of the EU directives the scale of this impact is of interest for responsible authorities. To further the insight of the effects of buildings and vegetation the RIVM has conducted a survey. In a relatively complex situation near the crossing of a highway and a busy local road particulate matter and nitrogen dioxide concentrations are monitored. The impact of vegetation could not be confirmed and is estimated to be absent or very minor at the survey site. Further investigation in which the structure of the vegetation is optimized might indicate the magnitude of the possible positive effect. The impact of buildings on air quality appears to be rather complex and can even result in higher concentrations at the lee site of the building. An important observation was the high contribution of local traffic. In the present study this contribution was clearly underestimated in the model calculation of the nitrogen dioxide concentrations and it is anticipated that this might occur more often. As a consequence the relative impact of measures directed at the emissions of traffic on the highway is overestimated.VROM-LM

De invloed van bebouwing en vegetatie op luchtkwaliteit. Scanning en scouting lucht

De invloed van bebouwing en vegetatie rond snelwegen op de luchtkwaliteit blijkt gering en in enkele gevallen complex van aard. Gebouwen en vegetatie kunnen van invloed zijn op de luchtkwaliteit van de directe omgeving. De mate waarin is in geval van overschrijdingen van de EU-richtlijnen van belang voor de verantwoordelijke bestuurders. Om meer inzicht te verkrijgen in deze effecten is onderzoek uitgevoerd door het RIVM. In een beperkt complexe situatie rondom een snelweg en een provinciale weg zijn luchtkwaliteitsmetingen voor PM10 en stikstofdioxide uitgevoerd.De invloed van vegetatie kon niet worden aangetoond en wordt voor de onderhavige situatie als zeer gering of afwezig geschat. Nader onderzoek waarbij de structuur van de vegetatie verder wordt geoptimaliseerd kan wellicht uitsluitsel geven over de mogelijk positieve invloed hiervan. De invloed van hoge gebouwen is zeer complex gebleken en kan leiden tot hogere concentraties stikstofdioxide aan de lijzijde van het gebouw. Een belangrijke observatie in het onderzoek is de hoge bijdrage van lokaal verkeer. In het onderhavige onderzoek werd dit duidelijk onderschat en verwacht wordt dat dit vaker plaatsvindt. Hierdoor kan de relatieve invloed van maatregelen gericht tegen de emissies van verkeer op de snelweg worden overschat.<br