50 research outputs found
Analysis of test beam data taken with a prototype of TPC with resistive Micromegas for the T2K Near Detector upgrade
In this paper we describe the performance of a prototype of the High Angle
Time Projection Chambers (HA-TPCs) that are being produced for the Near
Detector (ND280) upgrade of the T2K experiment. The two HA-TPCs of ND280 will
be instrumented with eight Encapsulated Resistive Anode Micromegas (ERAM) on
each endplate, thus constituting in total 32 ERAMs. This innovative technique
allows the detection of the charge emitted by ionization electrons over several
pads, improving the determination of the track position. The TPC prototype has
been equipped with the first ERAM module produced for T2K and with the HA-TPC
readout electronics chain and it has been exposed to the DESY Test Beam in
order to measure spatial and dE/dx resolution. In this paper we characterize
the performances of the ERAM and, for the first time, we compare them with a
newly developed simulation of the detector response. Spatial resolution better
than 800 and dE/dx resolution better than 10% are observed for
all the incident angles and for all the drift distances of interest. All the
main features of the data are correctly reproduced by the simulation and these
performances fully fulfill the requirements for the HA-TPCs of T2K
Characterization of Charge Spreading and Gain of Encapsulated Resistive Micromegas Detectors for the Upgrade of the T2K Near Detector Time Projection Chambers
An upgrade of the near detector of the T2K long baseline neutrino oscillation
experiment is currently being conducted. This upgrade will include two new Time
Projection Chambers, each equipped with 16 charge readout resistive Micromegas
modules. A procedure to validate the performance of the detectors at different
stages of production has been developed and implemented to ensure a proper and
reliable operation of the detectors once installed. A dedicated X-ray test
bench is used to characterize the detectors by scanning each pad individually
and to precisely measure the uniformity of the gain and the deposited energy
resolution over the pad plane. An energy resolution of about 10% is obtained. A
detailed physical model has been developed to describe the charge dispersion
phenomena in the resistive Micromegas anode. The detailed physical description
includes initial ionization, electron drift, diffusion effects and the readout
electronics effects. The model provides an excellent characterization of the
charge spreading of the experimental measurements and allowed the simultaneous
extraction of gain and RC information of the modules
Measurements of the and -induced Coherent Charged Pion Production Cross Sections on by the T2K experiment
We report an updated measurement of the -induced, and the first
measurement of the -induced coherent charged pion production
cross section on nuclei in the T2K experiment. This is measured in a
restricted region of the final-state phase space for which
GeV, and , and at a mean
(anti)neutrino energy of 0.85 GeV using the T2K near detector. The measured
CC coherent pion production flux-averaged cross section on
is . The new measurement
of the -induced cross section on is . The results are compatible with both the NEUT
5.4.0 Berger-Sehgal (2009) and GENIE 2.8.0 Rein-Sehgal (2007) model
predictions
Measurements of the νμ and ν¯μ -induced coherent charged pion production cross sections on C12 by the T2K experiment
We report an updated measurement of the
ν
μ
-induced, and the first measurement of the
¯
ν
μ
-induced coherent charged pion production cross section on
12
C
nuclei in the Tokai-to-Kamioka experiment. This is measured in a restricted region of the final-state phase space for which
p
μ
,
π
>
0.2
GeV
,
cos
(
θ
μ
)
>
0.8
and
cos
(
θ
π
)
>
0.6
, and at a mean (anti)neutrino energy of 0.85 GeV using the T2K near detector. The measured
ν
μ
charged current coherent pion production flux-averaged cross section on
12
C
is
(
2.98
±
0.37
(
stat
)
±
0.31
(
syst
)
+
0.49
−
0.00
(
Q
2
model
)
)
×
10
−
40
cm
2
. The new measurement of the
¯
ν
μ
-induced cross section on
12
C
is
(
3.05
±
0.71
(
stat
)
±
0.39
(
syst
)
+
0.74
−
0.00
(
Q
2
model
)
)
×
10
−
40
cm
2
. The results are compatible with both the NEUT 5.4.0 Berger-Sehgal (2009) and GENIE 2.8.0 Rein-Sehgal (2007) model predictions
Construction status and prospects of the Hyper-Kamiokande project
The Hyper-Kamiokande project is a 258-kton Water Cherenkov together with a 1.3-MW high-intensity neutrino beam from the Japan Proton Accelerator Research Complex (J-PARC). The inner detector with 186-kton fiducial volume is viewed by 20-inch photomultiplier tubes (PMTs) and multi-PMT modules, and thereby provides state-of-the-art of Cherenkov ring reconstruction with thresholds in the range of few MeVs. The project is expected to lead to precision neutrino oscillation studies, especially neutrino CP violation, nucleon decay searches, and low energy neutrino astronomy. In 2020, the project was officially approved and construction of the far detector was started at Kamioka. In 2021, the excavation of the access tunnel and initial mass production of the newly developed 20-inch PMTs was also started. In this paper, we present a basic overview of the project and the latest updates on the construction status of the project, which is expected to commence operation in 2027
L’antigene 70 KD di Neisseria gonorrhoeae: caratteristiche biologiche e prospettive vaccinali
Diagnostic Accuracy of Endocervicoscopy in Identifying and Grading Cervical Intraepithelial Neoplasia Lesion
Introduction: Colposcopy represents the second step of the diagnostic approach of cervical intraepithelial lesions. Limits of colposcopy in studying cervix are essentially related to cervical anatomy. Nowadays, endocervical courettage is the standard technique to examine endocervix. Endocervicoscopy is a new imaging technique for the diagnostic work-up of endocervix in patients with cervical intraepithelial neoplasia (CIN). Objective: To evaluate endocervicoscopy accuracy to identify and grade cervical intraepithelial lesion in comparison to other procedures employed into the diagnostic workup of cervical pathology. Methods: A total of 634 women who performed colposcopy, endocervicoscopy and cytological or histological sampling were included in a retrospective study. The agreement between the endocervicoscopic and the colposcopic impressions, minor and major changes, and between these imaging techniques and histological diagnosis was assessed for the entire cohort. χ2 test and k statistic were used in the statistical analysis. Results: The extension of the lesion resulted significantly greater at endocervicoscopy than at colposcopy. We showed a statistically significant association between colposcopy and endocervicoscopy findings. Overall, the correlation of minor or major findings between colposcopy and endocervicoscopy was statistically significant with a p value for all parameters <0.0001. Description of mosaic/punctuation, cuffed crypt (gland) openings and ridge sign showed a high k value (k = 0.68 [95% CI 0.64-0.73], k = 0.80 [95% CI 0.75-0.85], k = 0.78 [95% CI 0.64-0.90], respectively). The sensitivity (70.1%) and the specificity (77.0%) of endocervicoscopy for all CIN lesions were lower than colposcopy. Conclusion: Endocervicoscopy turned out to be a good method to identify and grade CIN lesions in a subset of patients where colposcopy was not satisfactory. It allowed us to overcome one of the limits of colposcopy in the evaluation of the squamo-columnar junction and to establish the real extension of the lesion into cervical cancer