-
N. Agafonov,
A. Aleksandrov,
O. Altinok,
M. Ambrosio,
A. Anokhina,
S Aoki,
A. Ariga,
T Ariga,
D. Autiero,
A. Badertscher, [......],
G. Wilqueta,
B. Wonsak,
V. Yakushev,
C.S. Yoona,
J Yoshida,
T Yoshioka,
Y. Zaitsev,
S. Zemskova,
A Zghiche,
R Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: The OPERA neutrino detector in the underground Gran Sasso Laboratory (LNGS) has been designed to perform the first detection of neutrino oscillations in direct appearance mode through the study of the $\nu_\mu\rightarrow\nu_\tau$ channel. The hybrid apparatus consists of an emulsion/lead target complemented by electronic detectors and it is placed in the high energy long-baseline CERN to LNGS beam (CNGS) 730 km away from the neutrino source. Runs with CNGS neutrinos were successfully carried out in 2008 and 2009. After a brief description of the beam, the experimental setup and the procedures used for the analysis of the neutrino events, we describe the topology and kinematics of a first candidate $\nu_\tau$ charged-current event satisfying the kinematical selection criteria. The background calculations and their cross-check are explained in detail and the significance of the event is assessed.
Physics Letters B 12/2012; · 3.95 Impact Factor
-
N. Agafonova,
A. Aleksandrov,
O. Altinok,
A. Anokhina,
S Aoki,
A. Ariga,
T Ariga,
D. Autiero,
A. Badertscher,
A Bagulya, [......],
G Wilquet,
B. Wonsak,
V. Yakushev,
C S Yoon,
T Yoshioka,
J Yoshida,
Y. Zaitsev,
S. Zemskova,
A Zghiche,
R Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: The OPERA experiment is based on a hybrid technology combining electronic detectors and nuclear emulsions. OPERA collected muon-neutrino interactions during the 2008 and 2009 physics runs of the CNGS neutrino beam, produced at CERN with an energy range of about 5-35 GeV. A total of $5.3 \times 10^{19}$ protons on target equivalent luminosity has been analysed with the OPERA electronic detectors: scintillator strips target trackers and magnetic muon spectrometers equipped with resistive plate gas chambers and drift tubes, allowing a detailed reconstruction of muon-neutrino interactions. Charged Current (CC) and Neutral Current (NC) interactions are identified, using the measurements in the electronic detectors, and the NC/CC ratio is computed. The momentum distribution and the charge of the muon tracks produced in CC interactions are analysed. Calorimetric measurements of the visible energy are performed for both the CC and NC samples. For CC events the Bjorken-$y$ distribution and the hadronic shower profile are computed. The results are compared to a detailed Monte Carlo simulation of the electronic detectors' response.
New Journal of Physics 12/2012; 13:053051. · 4.18 Impact Factor
-
The OPERA Collaboration,
T. Adam,
N. Agafonova,
A. Aleksandrov,
A. Anokhina,
S. Aoki,
A. Ariga,
T. Ariga,
D. Autiero,
A. Badertscher, [......],
J. L. Vuilleumier,
G. Wilquet,
B. Wonsak,
J. Wurtz,
C. S. Yoon,
J. Yoshida,
Y. Zaitsev,
S. Zemskova,
A. Zghiche,
R. Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: In spring 2012 CERN provided two weeks of a short bunch proton beam dedicated
to the neutrino velocity measurement over a distance of 730 km. The OPERA
neutrino experiment at the underground Gran Sasso Laboratory used an upgraded
setup compared to the 2011 measurements, improving the measurement time
accuracy. An independent timing system based on the Resistive Plate Chambers
was exploited providing a time accuracy of $\sim$1 ns. Neutrino and
anti-neutrino contributions were separated using the information provided by
the OPERA magnetic spectrometers. The new analysis profited from the precision
geodesy measurements of the neutrino baseline and of the CNGS/LNGS clock
synchronization. The neutrino arrival time with respect to the one computed
assuming the speed of light in vacuum is found to be $\delta t_\nu \equiv TOF_c
- TOF_\nu= (0.6 \pm 0.4\ (stat.) \pm 3.0\ (syst.))$ ns and $\delta
t_{\bar{\nu}} \equiv TOF_c - TOF_{\bar{\nu}} = (1.7 \pm 1.4\ (stat.) \pm 3.1\
(syst.))$ ns for $\nu_{\mu}$ and $\bar{\nu}_{\mu}$, respectively. This
corresponds to a limit on the muon neutrino velocity with respect to the speed
of light of $-1.8 \times 10^{-6} < (v_{\nu}-c)/c < 2.3 \times 10^{-6}$ at 90%
C.L. This new measurement confirms with higher accuracy the revised OPERA
result.
12/2012;
-
N. Yu. Agafonova,
P. Antonioli,
V. V. Ashikhmin,
G. Bari,
E. Bressan,
L. Evans,
M. Garbini,
P. Giusti,
A. S. Malguin,
R. Persiani, [......],
M. Spinetti,
L. Stanco,
M. Stipcevic,
M. Tenti,
F. Terranova, V. Tioukov,
B. Wonsak,
V. Yakushev,
Y. Zaitsev,
S. Zemskova
[show abstract]
[hide abstract]
ABSTRACT: The purpose of this work is to report the measurement of a time-shift in the
OPERA set-up in a totally independent way from Time Of Flight (TOF)
measurements of CNGS neutrino events. The LVD and OPERA experiments are both
installed in the same laboratory: LNGS. The relative position of the two
detectors, separated by an average distance of ~ 160 m, allows the use of very
high energy horizontal muons to cross-calibrate the timing systems of the two
detectors, using a TOF technique which is totally independent from TOF of CNGS
neutrino events. Indeed, the OPERA-LVD direction lies along the so-called
"Teramo anomaly", a region in the Gran Sasso massif where LVD has established,
many years ago, the existence of an anomaly in the mountain structure, which
exhibits a low m. w. e. thickness for horizontal directions. The "abundant"
high-energy horizontal muons (nearly 100 per year) going through LVD and OPERA
exist because of this anomaly in the mountain orography. The total live time of
the data in coincidence correspond to 1200 days from mid 2007 until March 2012.
The time coincidence study of LVD and OPERA detectors is based on 306 cosmic
horizontal muon events and shows the existence of a negative time shift in the
OPERA set-up of the order of deltaT(AB) = - (73 \pm 9) ns when two calendar
periods, A and B, are compared. This result shows a systematic effect in the
OPERA timing system from August 2008 until December 2011. The size of the
effect is comparable with the neutrino velocity excess recently measured by
OPERA. It is probably interesting not to forget that with the MRPC technology
developed by the ALICE Bologna group the TOF world record accuracy of 20 ps was
reached. That technology can be implemented at LNGS for a high precision
determination of TOF with the CNGS neutrino beams of an order of magnitude
smaller than the value of the OPERA systematic effect.
06/2012;
-
N. Agafonova,
A. Anokhina,
S. Aoki,
A. Ariga,
T. Ariga,
D. Autiero,
A. Badertscher,
A. Bagulya,
A. Bertolin,
M. Besnier, [......],
G. Wilquet,
B. Wonsak,
V. Yakushev,
C. S. Yoon,
T. Yoshioka,
J. Yoshida,
Y. Zaitsev,
S. Zemskova,
A. Zghiche,
R. Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: The OPERA detector at the Gran Sasso underground laboratory (LNGS) was used to measure the atmospheric muon charge ratio Rm=Nm+/Nm-R_{\mu}=N_{\mu^{+}}/N_{\mu^{-}} in the TeV energy region. We analyzed 403069 atmospheric muons corresponding to 113.4 days of livetime during the 2008 CNGS
run. We computed separately the muon charge ratio for single and for multiple muon events in order to select different energy
regions of the primary cosmic ray spectrum and to test the R
μ
dependence on the primary composition. The measured R
μ
values were corrected taking into account the charge-misidentification errors. Data have also been grouped in five bins of
the “vertical surface energy” ℰ
μ
cos θ. A fit to a simplified model of muon production in the atmosphere allowed the determination of the pion and kaon charge ratios
weighted by the cosmic ray energy spectrum.
European Physical Journal C 04/2012; 67(1):25-37. · 3.63 Impact Factor
-
A. Kayis-Topaksu,
G. Önengüt,
R. van Dantzig,
M. de Jong,
R.G.C. Oldeman,
M. Güler,
U. Köse,
P. Tolun,
M.G. Catanesi,
M.T. Muciaccia, [......],
F.R. Spada,
E. Barbuto,
C. Bozza,
G. Grella,
G. Romano,
C. Sirignano,
S. Sorrentino,
Y. Sato,
I. Tezuka,
The CHORUS Collaboration
[show abstract]
[hide abstract]
ABSTRACT: The CHORUS experiment, designed to search for νμ→ντ 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.
European Physical Journal C 04/2012; 51(4):775-785. · 3.63 Impact Factor
-
N Agafonova,
A Aleksandrov,
O Altinok,
A Anokhina,
S Aoki,
A Ariga,
T Ariga,
D Autiero,
A Badertscher,
A Bagulya, [......],
G Wilquet,
B Wonsak,
V Yakushev,
C S Yoon,
T Yoshioka,
J Yoshida,
Y Zaitsev,
S Zemskova,
A Zghiche,
R Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: A new method of momentum measurement of charged particles through multiple Coulomb scattering (MCS) in the OPERA lead-emulsion target is presented. It is based on precise measurements of track angular deviations carried out thanks to the very high resolution of nuclear emulsions. The algorithm has been tested with Monte Carlo pions. The results are found to describe within the expected uncertainties the data obtained from test beams. We also present a comparison of muon momenta evaluated through MCS in the OPERA lead-emulsion target with those determined by the electronic detectors for neutrino-charged current interaction events. The two independent measurements agree within the experimental uncertainties, and the results validate the algorithm developed for the emulsion detector of OPERA.
New Journal of Physics 01/2012; 14(1):013026. · 4.18 Impact Factor
-
The OPERA Collaboration,
T. Adam,
N. Agafonova,
A. Aleksandrov,
O. Altinok,
P. Alvarez Sanchez,
A. Anokhina,
S. Aoki,
A. Ariga,
T. Ariga, [......],
J. -L. Vuilleumier,
G. Wilquet,
B. Wonsak,
J. Wurtz,
V. Yakushev,
C. S. Yoon,
J. Yoshida,
Y. Zaitsev,
S. Zemskova,
A. Zghiche
[show abstract]
[hide abstract]
ABSTRACT: The OPERA neutrino experiment at the underground Gran Sasso Laboratory has
measured the velocity of neutrinos from the CERN CNGS beam over a baseline of
about 730 km. The measurement is based on data taken by OPERA in the years
2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the
OPERA detector, as well as a high precision geodesy campaign for the
measurement of the neutrino baseline, allowed reaching comparable systematic
and statistical accuracies. An arrival time of CNGS muon neutrinos with respect
to the one computed assuming the speed of light in vacuum of (6.5 +/-
7.4(stat.)((+8.3)(-8.0)sys.))ns was measured corresponding to a relative
difference of the muon neutrino velocity with respect to the speed of light
(v-c)/c =(2.7 +/-3.1(stat.)((+3.4)(-3.3)(sys.))x10^(-6). The above result,
obtained by comparing the time distributions of neutrino interactions and of
protons hitting the CNGS target in 10.5 microseconds long extractions, was
confrmed by a test performed at the end of 2011 using a short bunch beam
allowing to measure the neutrino time of flight at the single interaction
level.
09/2011;
-
A Kayis-Topaksu,
G Önengüt,
R Van Dantzig,
M De Jong,
R G C Oldeman,
M Güler,
U Köse,
P Tolun,
M G Catanesi,
M T Muciaccia, [......],
A. Satta,
F R Spada,
E Barbuto,
C Bozza,
G Grella,
G Romano,
C Sirignano,
S Sorrentino,
Y Sato,
I Tezuka
[show abstract]
[hide abstract]
ABSTRACT: The nuclear emulsion target of the CHORUS detector was exposed to the
wide-band neutrino beam of the CERN SPS of 27 GeV average neutrino energy from
1994 to 1997. In total about 100000 charged-current neutrino interactions with
at least one identified muon were located in the emulsion target and fully
reconstructed, using newly developed automated scanning systems. Charmed
particles were searched for by a program recognizing particle decays. The
observation of the decay in nuclear emulsion makes it possible to select a
sample with very low background and minimal kinematical bias. 2013
charged-current interactions with a charmed hadron candidate in the final state
were selected and confirmed through visual inspection. The charm production
rate induced by neutrinos relative to the charged-current cross-section is
measured to be sigma(nu_mu N -> mu- C X)/sigma(CC) = (5.75 +-0.32 stat +-0.30
syst)%. The charm production cross-section as a function of the neutrino energy
is also obtained. The results are in good agreement with previous measurements.
The charm-quark hadronization produces the following charmed hadrons with
relative fractions (in %): f_Dzero = 43.7+-4.5, f_Lambda_c^plus = 19.2+-4.2,
f_Dplus = 25.3+-4.2, and f_D_splus = 11.8+-4.7.
07/2011;
-
OPERA Collaboration,
N. Agafonova,
A. Anokhina,
S Aoki,
A. Ariga,
T Ariga,
D. Autiero,
A. Badertscher,
A Bagulya,
A Bertolin, [......],
G Wilquet,
B. Wonsak,
V. Yakushev,
C S Yoon,
T Yoshioka,
J Yoshida,
Y. Zaitsev,
S. Zemskova,
A Zghiche,
R Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: The OPERA detector at the Gran Sasso underground laboratory (LNGS) was used to measure the atmospheric muon charge ratio in the TeV energy region. We analyzed 403069 atmospheric muons corresponding to 113.4 days of livetime during the 2008 CNGS run. We computed separately the muon charge ratio for single and for multiple muon events in order to select different energy regions of the primary cosmic ray spectrum and to test the charge ratio dependence on the primary composition. The measured charge ratio values were corrected taking into account the charge-misidentification errors. Data have also been grouped in five bins of the "vertical surface energy". A fit to a simplified model of muon production in the atmosphere allowed the determination of the pion and kaon charge ratios weighted by the cosmic ray energy spectrum. Comment: 14 pages, 10 figures
03/2010;
-
N Agafonova,
A Anokhina,
S Aoki,
A Ariga,
T Ariga,
L Arrabito,
D Autiero,
A Badertscher,
A Bagulya,
F Bersani Greggio, [......],
J L Vuilleumier,
G Wilquet,
B Wonsak,
V Yakushev,
C S Yoon,
T Yoshioka,
J Yoshida,
Y Zaitsev,
A Zghiche,
R Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: The OPERA neutrino detector in the underground Gran Sasso Laboratory (LNGS) was designed to perform the first detection of neutrino oscillations in appearance mode through the study of νμ → ντ oscillations. The apparatus consists of an emulsion/lead target complemented by electronic detectors and it is placed in the high energy long-baseline CERN to LNGS beam (CNGS) 730 km away from the neutrino source. Runs with CNGS neutrinos were successfully carried out in 2007 and 2008 with the detector fully operational with its related facilities for the emulsion handling and analysis. After a brief description of the beam and of the experimental setup we report on the collection, reconstruction and analysis procedures of first samples of neutrino interaction events.
Journal of Instrumentation 06/2009; 4(06):P06020. · 1.87 Impact Factor
-
R Acquafredda,
T Adam,
N Agafonova,
P Alvarez Sanchez,
M Ambrosio,
A Anokhina,
S Aoki,
A Ariga,
T Ariga,
L Arrabito, [......],
T Waelchli,
M Weber,
G Wilquet,
B Wonsak,
J Wurtz,
V Yakushev,
C S Yoon,
Y Zaitsev,
A Zghiche,
R Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: The OPERA neutrino oscillation experiment has been designed to prove the appearance of ντ in a nearly pure νμ beam (CNGS) produced at CERN and detected in the underground Hall C of the Gran Sasso Laboratory, 730 km away from the source. In OPERA, τ leptons resulting from the interaction of ντ are produced in target units called bricks made of nuclear emulsion films interleaved with lead plates. The OPERA target contains 150000 of such bricks, for a total mass of 1.25 kton, arranged into walls interleaved with plastic scintillator strips. The detector is split into two identical supermodules, each supermodule containing a target section followed by a magnetic spectrometer for momentum and charge measurement of penetrating particles. Real time information from the scintillators and the spectrometers provide the identification of the bricks where the neutrino interactions occurred. The candidate bricks are extracted from the walls and, after X-ray marking and an exposure to cosmic rays for alignment, their emulsion films are developed and sent to the emulsion scanning laboratories to perform the accurate scan of the event. In this paper, we review the design and construction of the detector and of its related infrastructures, and report on some technical performances of the various components. The construction of the detector started in 2003 and it was completed in Summer 2008. The experiment is presently in the data taking phase. The whole sequence of operations has proven to be successful, from triggering to brick selection, development, scanning and event analysis.
Journal of Instrumentation 04/2009; 4(04):P04018. · 1.87 Impact Factor
-
A Anokhina,
S Aoki,
A Ariga,
L Arrabito,
D Autiero,
A Badertscher,
F Bay,
A Bergnoli,
F Bersani Greggio,
M Besnier, [......],
J L Vuilleumier,
G Wilquet,
B Wonsak,
J Wurtz,
C S Yoon,
J Yoshida,
Y Zaitsev,
S Zemskova,
A Zghiche,
R Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: The OPERA neutrino oscillation experiment is based on the use of the Emulsion Cloud Chamber (ECC). In the OPERA ECC, nuclear emulsion films acting as very high precision tracking detectors are interleaved with lead plates providing a massive target for neutrino interactions. We report on studies related to the effects occurring from the contact between emulsion and lead. A low radioactivity lead is required in order to minimize the number of background tracks in emulsions and to achieve the required performance in the reconstruction of neutrino events. It was observed that adding other chemical elements to the lead, in order to improve the mechanical properties, may significantly increase the level of radioactivity on the emulsions. A detailed study was made in order to choose a lead alloy with good mechanical properties and an appropriate packing technique so as to have a low enough effective radioactivity.
Journal of Instrumentation 07/2008; 3(07):P07002. · 1.87 Impact Factor
-
I Kreslo,
M Cozzi,
A Ereditato,
M Hess,
J Knuesel,
I Laktineh,
M Messina,
U Moser,
C Pistillo,
K Pretzl,
L Scotto,
G Sirri,
H.-U Schutz, V Tioukov
[show abstract]
[hide abstract]
ABSTRACT: The extensive use of nuclear emulsions as precise tracking detectors in experimental physics has been made possible due to recent advances in the production of novel emulsion films and to the development of automatic scanning devices. The scanning speed of such systems has ex-ceeded the level of 20 cm 2 of emulsion surface per hour. High-speed automatic scanning systems, such as those developed by the OPERA Collaboration, are able to reconstruct particle tracks in nu-clear emulsions with excellent accuracy. However, the high-magnification oil immersion objectives used in these systems assume deposition and removal of oil onto and from the emulsion films. This is a major technological obstacle in the automatization of the emulsion feeding to the microscope, as required for large scale use as in the case of the OPERA neutrino oscillation experiment. In order to overcome this problem, an innovative technique of nuclear emulsion films scanning with the use of dry objective lenses has been developed and successfully applied to the experiment.
01/2008; 3.
-
L. Arrabito,
C Bozza,
S Buontempo,
L. Consiglio,
M. Cozzi,
N D'Ambrosio,
G De Lellis,
M. De Serio,
F Di Capua,
D. Di Ferdinando, [......],
N. Savvinov,
A. Schembri,
L. Scotto Lavina,
S Simone,
M. Sioli,
C Sirignano,
G. Sirri,
P Strolin, V Tioukov,
T. Waelchli
[show abstract]
[hide abstract]
ABSTRACT: The OPERA experiment, designed to conclusively prove the existence of $\rm \nu_\mu \to \nu_\tau$ oscillations in the atmospheric sector, makes use of a massive lead-nuclear emulsion target to observe the appearance of $\rm \nu_\tau$'s in the CNGS $\rm \nu_\mu$ beam. The location and analysis of the neutrino interactions in quasi real-time required the development of fast computer-controlled microscopes able to reconstruct particle tracks with sub-micron precision and high efficiency at a speed of 20 cm^2 / h. This paper describes the performance in particle track reconstruction of the European Scanning System, a novel automatic microscope for the measurement of emulsion films developed for OPERA. Comment: 13 pages, 10 figures
05/2007;
-
G De Lellis,
S Buontempo,
F Di Capua,
A Marotta,
P. Migliozzi,
Y. Petukhov,
C. Pistillo,
A Russo,
L. Scotto Lavina,
P Strolin, V Tioukov,
A. Ariga,
N. Naganawa,
T Toshito,
Y. Furusawa,
N. Yasuda
[show abstract]
[hide abstract]
ABSTRACT: Beams of Carbon nuclei are used or planned to be used in various centers for cancer treatment around the world because of their therapeutic advantages over proton beams. The knowledge of the fragmentation of Carbon nuclei when they interact with the human body is important to evaluate the spatial profile of their energy deposition in the tissues, hence the damage to the tissues neighboring the tumor. In this respect, the identification of the fragmentation products is a key element. We present in this paper the charge measurement of about 3000 fragments produced by the interaction of $^{12}$C nuclei with an energy of 400 MeV/nucleon in a detector simulating the density of the human body. The nuclear emulsion technique is used, by means of the so-called Emulsion Cloud Chamber. In order to achieve the large dynamical range required for the charge measurement, the recently developed techniques of the emulsion controlled fading are used. The nuclear emulsions are inspected using fast automated microscopes recently developed. A charge assignment efficiency of more than 99% is achieved. The separation of Hydrogen, Helium, Lithium, Berillium, Boron and Carbon can be achieved at two standard deviations or considerably more, according to the track length available for the measurement. Comment: 15 pages, 8 figures
03/2007;
-
L. Arrabito,
D. Autiero,
C Bozza,
S Buontempo,
Y. Caffari,
L. Consiglio,
M. Cozzi,
N D'Ambrosio,
G De Lellis,
M. De Serio, [......],
A Russo,
N. Savvinov,
A. Schembri,
L. Scotto Lavina,
S Simone,
M. Sioli,
C Sirignano,
G. Sirri,
P Strolin, V Tioukov
[show abstract]
[hide abstract]
ABSTRACT: We have studied the performance of a new algorithm for electron/pion separation in an Emulsion Cloud Chamber (ECC) made of lead and nuclear emulsion films. The software for separation consists of two parts: a shower reconstruction algorithm and a Neural Network that assigns to each reconstructed shower the probability to be an electron or a pion. The performance has been studied for the ECC of the OPERA experiment [1]. The $e/\pi$ separation algorithm has been optimized by using a detailed Monte Carlo simulation of the ECC and tested on real data taken at CERN (pion beams) and at DESY (electron beams). The algorithm allows to achieve a 90% electron identification efficiency with a pion misidentification smaller than 1% for energies higher than 2 GeV.
02/2007;
-
A. Kayis-Topaksu,
G. Önengüt,
R. van Dantzig,
M. de Jong,
R.G.C. Oldeman,
M. Güler,
U. Köse,
P. Tolun,
M.G. Catanesi,
M.T. Muciaccia, [......],
F.R. Spada,
E. Barbuto,
C. Bozza,
G. Grella,
G. Romano,
C. Sirignano,
S. Sorrentino,
Y. Sato,
I. Tezuka,
The CHORUS Collaboration
[show abstract]
[hide abstract]
ABSTRACT: In this paper a search for associated charm production both in neutral and charged current ν-nucleus interactions is presented.
The improvement of automatic scanning systems in the CHORUS experiment allows an efficient search to be performed in emulsion
for short-lived particles. Hence a search for rare processes, like the associated charm production, becomes possible through
the observation of the double charm-decay topology with a very low background. About 130000ν interactions located in the
emulsion target have been analysed. Three events with two charm decays have been observed in the neutral-current sample with
an estimated background of 0.18±0.05. The relative rate of the associated charm cross-section in deep inelastic ν interactions,
σ(cc̄ν)/σNC
DIS=(3.62+2.95
-2.42(stat)±0.54(syst))×10-3 has been measured. One event with two charm decays has been observed in charged-current νμ interactions with an estimated background of 0.18±0.06 and the upper limit on associated charm production in charged-current
interactions at 90% C.L. has been found to be σ(cc̄μ-)/σCC<9.69×10-4.
European Physical Journal C 01/2007; 52(3):543-552. · 3.63 Impact Factor
-
L. Arrabito,
E. Barbuto,
C. Bozza,
S. Buontempo,
L. Consiglio,
D. Coppola,
M. Cozzi,
J. Damet,
N. D’Ambrosio,
G. De Lellis, [......],
A. Schembri,
L. Scotto Lavina,
S. Simone,
M. Sioli,
C. Sirignano,
G. Sirri,
G. Sorrentino,
P. Strolin, V. Tioukov,
T. Waelchli
[show abstract]
[hide abstract]
ABSTRACT: The use of nuclear emulsions in very large physics experiments is now possible thanks to the recent improvements in the industrial production of emulsions and to the development of fast automated microscopes. In this paper the hardware performances of the European Scanning System (ESS) are described. The ESS is a very fast automatic system developed for the mass scanning of the emulsions of the OPERA experiment, which requires microscopes with scanning speeds of in an emulsion volume of thickness.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 05/2006;
-
L. Arrabito,
D. Autiero,
E Barbuto,
C Bozza,
S Cecchini,
L. Consiglio,
M. Cozzi,
N D'Ambrosio,
Y Declais,
G De Lellis, [......],
G Romano,
G Rosa,
P. Royole-Degieux,
S Simone,
M. Sioli,
C Sirignano,
G. Sirri,
G. Sorrentino,
M. Spurio, V Tioukov
[show abstract]
[hide abstract]
ABSTRACT: We describe a possible search for muonic radioactivity from lead nuclei using the base elements ("bricks" composed by lead and nuclear emulsion sheets) of the long-baseline OPERA neutrino experiment. We present the results of a Monte Carlo simulation concerning the expected event topologies and estimates of the background events. Using few bricks, we could reach a good sensitivity level.
07/2005;
