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Andreev, N.

Publications and source records attributed to Andreev, N..

16 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Mu2e Run I Sensitivity Projections for the Neutrinoless Conversion Search in Aluminum

The Mu2e experiment at Fermilab will search for the neutrinoless conversion in the field of an aluminum nucleus. The Mu2e data-taking plan assumes two running periods, Run I and Run II, separated by an approximately two-year-long shutdown. This paper presents an estimate of the expected Mu2e Run I search sensitivity and includes a detailed discussion of the background sources, uncertainties of their prediction, analysis procedures, and the optimization of the experimental sensitivity. The expected Run I discovery sensitivity is , with a total expected background of events. In the absence of a signal, the expected upper limit is at 90% CL. This represents a three order of magnitude improvement over the current experimental limit of at 90% CL set by the SINDRUM II experiment.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Long-term Variability of H{sub 2}CO Masers in Star-forming Regions

We present results of a multi-epoch monitoring program on variability of 6 cm formaldehyde (H{sub 2}CO) masers in the massive star-forming region NGC 7538 IRS 1 from 2008 to 2015, conducted with the Green Bank Telescope, the Westerbork Radio Telescope , and the Very Large Array. We found that the similar variability behaviors of the two formaldehyde maser velocity components in NGC 7538 IRS 1 (which was pointed out by Araya and collaborators in 2007) have continued. The possibility that the variability is caused by changes in the maser amplification path in regions with similar morphology and kinematics is discussed. We also observed 12.2 GHz methanol and 22.2 GHz water masers toward NGC 7538 IRS 1. The brightest maser components of CH{sub 3}OH and H{sub 2}O species show a decrease in flux density as a function of time. The brightest H{sub 2}CO maser component also shows a decrease in flux density and has a similar LSR velocity to the brightest H{sub 2}O and 12.2 GHz CH{sub 3}OH masers. The line parameters of radio recombination lines and the 20.17 and 20.97 GHz CH{sub 3}OH transitions in NGC 7538 IRS 1 are also reported. In addition, we observed five other 6 cm formaldehyde maser regions. We found no evidence of significant variability of the 6 cm masers in these regions with respect to previous observations, the only possible exception being the maser in G29.96−0.02. All six sources were also observed in the H{sub 2}{sup 13}CO isotopologue transition of the 6 cm H{sub 2}CO line; H{sub 2}{sup 13}CO absorption was detected in five of the sources. Estimated column density ratios [H{sub 2}{sup 12}CO]/[H{sub 2}{sup 13}CO] are reported.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Development of a 15 T Nb 3 Sn accelerator dipole demonstrator at Fermilab

Here, a 100 TeV scale Hadron Collider (HC) with a nominal operation field of at least 15 T is being considered for the post-LHC era, which requires using the Nb 3 Sn technology. Practical demonstration of this field level in an accelerator-quality magnet and substantial reduction of the magnet costs are the key conditions for realization of such a machine. FNAL has started the development of a 15 T Nb 3 Sn dipole demonstrator for a 100 TeV scale HC. The magnet design is based on 4-layer shell type coils, graded between the inner and outer layers to maximize the performance and reduce the cost. The experience gained during the Nb 3 Sn magnet R&D is applied to different aspects of the magnet design. This paper describes the magnetic and structural designs and parameters of the 15 T Nb 3 Sn dipole and the steps towards the demonstration model fabrication.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Nb 3 Sn RRP® strand and Rutherford cable development for a 15 T dipole demonstrator

Keystoned Rutherford cables made of 28 strands and with a stainless steel core were developed and manufactured using 1 mm Nb3Sn composite wires produced by Oxford Superconducting Technology with 127 and 169 restacks using the Restacked-Rod-Process ® . Furthermore, the performance and properties of these cables were studied to evaluate possible candidates for 15 T accelerator magnets.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Performance of conduction cooled splittable superconducting magnet package for linear accelerators

New Linear Superconducting Accelerators need a superconducting magnet package installed inside SCRF Cryomodules to focus and steer electron or proton beams. A superconducting magnet package was designed and built as a collaborative effort of FNAL and KEK. The magnet package includes one quadrupole, and two dipole windings. It has a splittable in the vertical plane configuration, and features for conduction cooling. The magnet was successfully tested at room temperature, in a liquid He bath, and in a conduction cooling experiment. The paper describes the design and test results including: magnet cooling, training, and magnetic measurements by rotational coils. Furthermore, the effects of superconductor and iron yoke magnetization, hysteresis, and fringe fields are discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Quench Performance of the First Twin-aperture 11 T Dipole for LHC upgrades

FNAL and CERN are developing a twin-aperture 11 T $Nb_{3}Sn$ dipole suitable for installation in the LHC. A single-aperture 2-m long dipole demonstrator and two 1-m long dipole models have been fabricated and tested at FNAL in 2012-2014. The two 1 m long collared coils were then assembled into the first twin-aperture $Nb_{3}Sn$ demonstrator dipole and tested. Test results of this twin-aperture $Nb_{3}Sn$ dipole model are reported and discussed.

Zlobin, A. V.↗
DOE OSTI2015

11 T Twin-Aperture Nb$_3$Sn Dipole Development for LHC Upgrades

FNAL and CERN are developing a twin-aperture 11 T Nb3Sn dipole suitable for installation in the LHC. This paper describes the design and parameters of the 11 T dipole developed at FNAL for the LHC upgrades in both single-aperture and twin-aperture configurations, and presents details of the constructed dipole models. Results of studies of magnet quench performance, quench protection and magnetic measurements performed using short 1 m long coils in the dipole mirror and single-aperture configurations are reported and discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Magnetic and Structural Design of a 15 T $Nb_3Sn$ Accelerator Depole Model

Hadron Colliders (HC) are the most powerful discovery tools in modern high energy physics. A 100 TeV scale HC with a nominal operation field of at least 15 T is being considered for the post-LHC era. The choice of a 15 T nominal field requires using the Nb3Sn technology. Practical demonstration of this field level in an accelerator-quality magnet and substantial reduction of the magnet costs are the key conditions for realization of such a machine. FNAL has started the development of a 15 T $Nb_{3}Sn$ dipole demonstrator for a 100 TeV scale HC. The magnet design is based on 4-layer shell type coils, graded between the inner and outer layers to maximize the performance. The experience gained during the 11-T dipole R&D campaign is applied to different aspects of the magnet design. This paper describes the magnetic and structural designs and parameters of the 15 T $Nb_3Sn$ dipole and the steps towards the demonstration model.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Room temperature resistive state switching with hysteresis in GdMnO{sub 3} thin film with low threshold voltage

In this paper, we report a room temperature resistive state switching with hysteresis, in a thin film of GdMnO{sub 3} grown on NdGaO{sub 3} substrate. The switched states have a resistance ratio ≈10{sup 3}. The switching is unipolar in nature, with a low set voltage <3 V, while the reset voltage <0.3 V. The switching occurs between a high resistance polaronic insulating state and a low resistance metallic state. The resistance state transition has been ascribed to an electronic mechanism that originates from co-existing phases (created by charge disproportionation) that can undergo a percolative transition enabled by the applied bias.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Study of interstellar molecular clouds using formaldehyde absorption toward extragalactic radio sources

We present new Very Large Array 6 cm H{sub 2}CO observations toward four extragalactic radio continuum sources (B0212+735, 3C 111, NRAO 150, and BL Lac) to explore the structure of foreground Galactic clouds as revealed by absorption variability. This project adds a new epoch in the monitoring observations of the sources reported by Marscher and collaborators in the mid-1990s. Our new observations confirm the monotonic increase in H{sub 2}CO absorption strength toward NRAO 150. We do not detect significant variability of our 2009 spectra with respect to the 1994 spectra of 3C111, B0212+735, and BL Lac; however, we find significant variability of the 3C111 2009 spectrum with respect to archive observations conducted in 1991 and 1992. Our analysis supports that changes in absorption lines could be caused by chemical and/or geometrical gradients in the foreground clouds and not necessarily by small-scale (∼10 AU) high-density molecular clumps within the clouds.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Cryogenic performance of a conduction-cooling splittable quadrupole magnet for ILC cryomodules

A conduction-cooled splittable superconducting quadrupole magnet was designed and fabricated at Fermilab for use in cryomodules of the International Linear Collider (ILC) type, in which the magnet was to be assembled around the beam tube to avoid contaminating the ultraclean superconducting radio frequency cavity volume. This quadrupole was first tested in a liquid helium bath environment at Fermilab, where its quench and magnetic properties were characterized. Because the device is to be cooled by conduction when installed in cryomodules, a separate test with a conduction-cooled configuration was planned at KEK and Fermilab. The magnet was converted to a conduction-cooled configuration by adding conduction-cooling passages made of high-purity aluminum. Efforts to convert and refabricate the magnet into a cryostat equipped with a double-stage pulse-tube-type cryocooler began in 2011, and a thermal performance test, including a magnet excitation test of up to 30 A, was conducted at KEK. In this test, the magnet with the conduction-cooled configuration was successfully cooled to 4 K within 190 h, with an acceptable heat load of less than 1 W at 4 K. It was also confirmed that the conduction-cooled splittable superconducting quadrupole magnet was practical for use in ILC-type cryomodules.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Recent progress and tests of radiation resistant impregnation materials for Nb{sub 3}Sn coils

Fermilab is collaborating with Lawrence Berkeley National Laboratory (LBNL) and Brookhaven National Laboratory (BNL) (US-LARP collaboration) to develop a large-aperture Nb{sub 3}Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade. An important component of this work is the development of materials that are sufficiently radiation resistant for use in critical areas of the upgrade. This paper describes recent progress in characterization of materials, including the baseline CTD101K epoxy, cyanate ester blends, and Matrimid 5292, a bismaleimide-based system. Structural properties of “ten stacks” of cable impregnated with these materials are tested at room and cryogenic temperatures and compared to the baseline CT-101K. Experience with potting 1 and 2 meter long coils with Matrimid 5292 are described. Test results of a single 1-m coil impregnated with Matrimid 5292 are reported and compared to similar coils impregnated with the traditional epoxy.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Field Quality Study of a 1-m-Long Single-Aperture 11-T Nb$_3$Sn Dipole Model for LHC Upgrades

FNAL and CERN are carrying out a joint R&D program with the goal of building a 5.5-m-long twin-aperture 11-T Nb_3Sn dipole prototype that is suitable for installation in the LHC. An important part of the program is the development and test of a series of short single-aperture and twin-aperture dipole models with a nominal field of 11 T at the LHC operation current of 11.85 kA and 20% margin. This paper presents the results of magnetic measurements of a 1-m-long single-aperture Nb_3Sn dipole model fabricated and tested recently at FNAL, including geometrical field harmonics and effects of coil magnetization and iron yoke saturation.

43 PARTICLE ACCELERATORS↗