Abstract
The Japan Atomic Energy Agency (JAEA) has been proposing an accelerator-driven nuclear transmutation system (ADS) as a future nuclear system. In preparation for the actual design of the CW ...proton linac for the JAEA-ADS, we are now prototyping a low-
β
(≈ 0.2) single-spoke cavity. The cavity fabrication started in 2020. Most of the cavity parts were shaped in fiscal year 2020 by press-forming and machining. In 2021, we started welding the shaped cavity parts together. By preliminarily investigating the optimum welding conditions using mock-up test pieces, each cavity part was joined together with smooth welding beads. So far, we have fabricated the body section and the beam port sections. By measuring the resonant frequency of the temporarily assembled cavity, it was confirmed that there were no significant problems with the cavity fabrication.
Abstract
We present the cost-effective production of superconducting
radio frequency (SRF) cavities made of medium grain (MG) niobium
(Nb) discs directly sliced from forged and annealed billet. This
...production method provides clean surface conditions and reliable
mechanical characteristics with sub-millimeter average grain size
resulting in stable SRF cavity production. We propose to apply this
material to particle accelerator in the science and industrial
applications. The science applications require high field
gradients(≥ 30 MV/m) particularly in pulsed mode. The
industrial applications require high
Q
0
values with moderate
gradients (∼ 20 MV/m) in CW mode operation. This paper
describes the MG Nb disc production recently demonstrated and
discusses future prospects for application in advanced particle
accelerators in the science and industrial applications.
Purpose:
Delivered doses in an anthropomorphic phantom were evaluated by using the RADPOS system for proton beam therapy.
Methods:
The RADPOS in vivo dosimetry system combines an electromagnetic ...positioning sensor with MOSFET dosimetry, allowing simultaneous online measurements of dose and spatial position. Through the RADPOS system, dose evaluation points can be determined. In vivo proton dosimetry was evaluated by using the RADPOS system and anthropomorphic head and neck phantom. MOSFET doses measured at 3D positions obtained with the RADPOS were compared to the treatment plan values that were calculated by a simplified Monte Carlo (SMC) method. Although the MOSFET response depends strongly on the linear energy transfer (LET) of proton beam, the MOSFET responses to proton beams were corrected with the SMC. Here, the SMC calculated only dose deposition determined by the experimental depth–dose distribution and lateral displacement of protons due to both multiple scattering effect in materials and incident angle. As a Result, the SMC could quickly calculate accurate doses in even heterogeneities.
Results:
In vivo dosimetry by using the RADPOS, as well as the MOSFET doses agreed in comparison with calculations by the SMC in the range of −3.0% to 8.3%. Most measurement errors occurred because of the uncertainties of dose calculations due to the position error of 1 mm.
Conclusion:
We evaluated the delivered doses in the anthropomorphic phantom by using the RADPOS system for proton beam therapy. The MOSFET doses agreed in comparison with calculations by the SMC within the measurement error. Therefore, we could successfully control the uncertainties of the measurement positions by using the RADPOS system within 1 mm in in vivo proton dosimetry. We aim for the clinical application of in vivo proton dosimetry with this RADPOS system.
Sugar-containing PPVs, poly{2-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-5-methoxy-p-phenylenevinylene-alt-p-phenylenevinylene} (PPV-GlcNAc) and ...poly{2,5-bis-O-(β-d-glucopyranosyl)-p-phenylenevinylene-alt-p-phenylenevinylene} (PPV-Glc2), were synthesized via Heck reaction of p-divinylbenzene (DVB) with O-glycosylated hydroquinones, 2,5-dibromo-4-methoxyphenyl 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranoside (3) and 1,4-bis(O-2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)-2,5-dibromobenzene (6), respectively. Acetyl protecting groups of the PPVs are completely removable under mild conditions (yield 69−87%). The structures were confirmed using 1H NMR and IR spectra. Size exclusion chromatography (SEC) (eluent: DMF, polystyrene standards) measurements indicated that respective M n and M w/M n values of the obtained polymers are 4.49 × 103 and 2.35 (PPV-GlcNAc) and 3.86 × 103 and 1.39 (PPV-Glc2). These sugar-containing PPVs are soluble in water/DMF (8/2, v/v) and are recognized by Concanavalin A (Con A), d-glucose-binding protein. Blue shift of λmax of the conjugated polymer backbone was confirmed when the glucose-substituted PPV interacts with Con A. Based on those binding properties, these results revealed that the obtained PPVs with pendant sugars have capabilities for detection of biological stimuli.
The reconstruction and calibration algorithms used to calculate missing transverse momentum (Formula: see text ) with the ATLAS detector exploit energy deposits in the calorimeter and tracks ...reconstructed in the inner detector as well as the muon spectrometer. Various strategies are used to suppress effects arising from additional proton-proton interactions, called pileup, concurrent with the hard-scatter processes. Tracking information is used to distinguish contributions from the pileup interactions using their vertex separation along the beam axis. The performance of the Formula: see text reconstruction algorithms, especially with respect to the amount of pileup, is evaluated using data collected in proton-proton collisions at a centre-of-mass energy of 8 Formula: see text during 2012, and results are shown for a data sample corresponding to an integrated luminosity of Formula: see text. The simulation and modelling of Formula: see text in events containing a
boson decaying to two charged leptons (electrons or muons) or a
boson decaying to a charged lepton and a neutrino are compared to data. The acceptance for different event topologies, with and without high transverse momentum neutrinos, is shown for a range of threshold criteria for Formula: see text , and estimates of the systematic uncertainties in the Formula: see text measurements are presented.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A measurement of the Formula: see text and Formula: see text production cross sections in final states with either two same-charge muons, or three or four leptons (electrons or muons) is presented. ...The analysis uses a data sample of proton-proton collisions at Formula: see text TeV recorded with the ATLAS detector at the Large Hadron Collider in 2015, corresponding to a total integrated luminosity of 3.2 fbFormula: see text. The inclusive cross sections are extracted using likelihood fits to signal and control regions, resulting in Formula: see text pb and Formula: see text pb, in agreement with the Standard Model predictions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
An inclusive search for a new-physics signature of lepton-jet resonances has been performed by the ATLAS experiment. Scalar leptoquarks, pair-produced in pp collisions at s = 13 TeV at the large ...hadron collider, have been considered. An integrated luminosity of 3.2 fb−1, corresponding to the full 2015 dataset was used. First (second) generation leptoquarks were sought in events with two electrons (muons) and two or more jets. The observed event yield in each channel is consistent with Standard Model background expectations. The observed (expected) lower limits on the leptoquark mass at 95% confidence level are 1100 and 1050 GeV (1160 and 1040 GeV) for first and second generation leptoquarks, respectively, assuming a branching ratio into a charged lepton and a quark of 100%. Upper limits on the aforementioned branching ratio are also given as a function of leptoquark mass. Compared with the results of earlier ATLAS searches, the sensitivity is increased for leptoquark masses above 860 GeV, and the observed exclusion limits confirm and extend the published results.
A search for strongly produced supersymmetric particles is conducted using signatures involving multiple energetic jets and either two isolated leptons (
or Formula: see text) with the same electric ...charge or at least three isolated leptons. The search also utilises
-tagged jets, missing transverse momentum and other observables to extend its sensitivity. The analysis uses a data sample of proton-proton collisions at Formula: see text TeV recorded with the ATLAS detector at the Large Hadron Collider in 2015 corresponding to a total integrated luminosity of 3.2 fbFormula: see text. No significant excess over the Standard Model expectation is observed. The results are interpreted in several simplified supersymmetric models and extend the exclusion limits from previous searches. In the context of exclusive production and simplified decay modes, gluino masses are excluded at Formula: see text confidence level up to 1.1-1.3 TeV for light neutralinos (depending on the decay channel), and bottom squark masses are also excluded up to 540 GeV. In the former scenarios, neutralino masses are also excluded up to 550-850 GeV for gluino masses around 1 TeV.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Results of a search for new phenomena in events with at least three photons are reported. Data from proton-proton collisions at a centre-of-mass energy of 8 TeV, corresponding to an integrated ...luminosity of 20.3 fbFormula: see text, were collected with the ATLAS detector at the LHC. The observed data are well described by the Standard Model. Limits at the 95 % confidence level on new phenomena are presented based on the rate of events in an inclusive signal region and a restricted signal region targeting the rare decay Formula: see text, as well as di-photon and tri-photon resonance searches. For a Standard Model Higgs boson decaying to four photons via a pair of intermediate pseudoscalar particles (
), limits are found to be Formula: see text for 10 GeV Formula: see text 62 GeV. Limits are also presented for Higgs boson-like scalars (
) for Formula: see text 125 GeV, and for a Formula: see text decaying to three photons via Formula: see text. Additionally, the observed limit on the branching ratio of the
boson decay to three photons is found to be BRFormula: see text, a result five times stronger than the previous result from LEP.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Fiducial cross-sections for ... production with one or two additional b-jets are reported, using an integrated luminosity ...of 20.3 fb... of proton-proton collisions at a centre-of-mass energy of 8 TeV at the Large Hadron Collider, collected with the ATLAS detector. The cross-section times branching ratio for ... events with at least one additional b-jet is measured to be 950 ... 70 (stat.) ... (syst.) fb in the lepton-plus-jets channel and 50 ... 10 (stat.) ... (syst.) fb in the ... channel. The cross-section times branching ratio for events with at least two additional b-jets is measured to be 19.3 ... 3.5 (stat.) ... 5.7 (syst.) fb in the dilepton channel (..., ..., and ee) using a method based on tight selection criteria, and 13.5 ... 3.3 (stat.) ... 3.6 (syst.) fb using a looser selection that allows the background normalisation to be extracted from data. The latter method also measures a value of 1.30 ... 0.33 (stat.) ... 0.28 (syst.)% for the ratio of ... production with two additional b-jets to ... production with any two additional jets. All measurements are in good agreement with recent theory predictions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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