Physics beyond the Standard Model predicts the possible existence of new particles that can be searched at the low energy frontier in the sub-eV range. The OSQAR photon regeneration experiment looks ...for "Light Shining through a Wall" from the quantum oscillation of optical photons into "Weakly Interacting Sub-eV Particles", such as axion or Axion-Like Particles (ALPs), in a 9 T transverse magnetic field over the unprecedented length of 2 × 14.3 m. In 2014, this experiment has been run with an outstanding sensitivity, using an 18.5 W continuous wave laser emitting in the green at the single wavelength of 532 nm. No regenerated photons have been detected after the wall, pushing the limits for the existence of axions and ALPs down to an unprecedented level for such a type of laboratory experiment. The di-photon couplings of possible pseudoscalar and scalar ALPs can be constrained in the nearly massless limit to be less than 3.5·10 −8 GeV −1 and 3.2·10 −8 GeV −1 , respectively, at 95% Confidence Level.
OSQAR chameleon afterglow search experiment Sulc, M.; Pugnat, P.; Ballou, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2019, Volume:
936
Journal Article
Peer reviewed
Open access
OSQAR experiment has been extended to the quest of chameleon particles with environment-dependent mass from the search of a magnetic afterglow effect. OSQAR-CHASE (chameleon afterglow search) has ...been run in 2017 using one spare LHC dipole providing a 9 T transverse magnetic field with an 18.5 W laser and state-of-the art CCD detector. Experimental results with and without magnetic field were preliminary analyzed and no clear evidence for a photon-coupled chameleons was confirmed. The very weak false signals was observed with decay time 4300 s. It can be explained by decrease of dark current from initial higher values during CCD cooling in detection phase. Increasing of the sensitivity of the OSQAR-CHASE experiment over the previous GammeV reference experiment assumes that the present coupling constant limit can be reduced around factor of 4.
•OSQAR laser experiment at CERN has been extended to the quest of chameleon particles.•The 18 W laser was shining through a 9 T magnetic field of spare LHC dipole.•The very weak 4.3 Hz false signals was observed after laser switch-off.•There was no difference in afterglow optical signal with and without magnetic field.•The present chameleon–photon coupling constant limit can be reduced by factor of 4.
The Grenoble Hybrid magnet is a modular platform using resistive and superconducting technologies to produce various DC high magnetic field and flux configurations for the scientific community. They ...range from 43 T in 34 mm diameter with 24 MW electrical power to 9 T in 800 mm diameter when the superconducting coil is used alone. Thanks to the ongoing upgrade of the electrical power installation at LNCMI-Grenoble to 30 MW, and possibly to 36 MW, the opportunity to increase the total field well above 45 T in the near future is anticipated and studied in detail. The key design parameters will be recalled comprising the specifically developed Nb-Ti/Cu conductor, the large-bore outsert superconducting coil, the magnet cryostat with its structure including the eddy-current shield, the cryogenic line for the interconnection with the cryogenic satellite and the dedicated 150 l/h He liquefaction plant. All components of the superconducting part of the hybrid magnet platform have been built, tested and delivered to LNCMI-Grenoble, where integration and final assembly are continuing. The status of the project will be presented with the main problems encountered and solved. It includes the recent commissioning tests of the cryogenic satellite producing the pressurized superfluid He at 1.8 K as well as the successful powering tests of the specially developed current leads at ultimate current and under fully degraded cooling conditions simulating the worst-case accidental scenario.
Recent theoretical and experimental studies highlight the possibility of new fundamental particle physics beyond the Standard Model that can be probed by sub-eV energy experiments. The OSQAR photon ...regeneration experiment looks for “Light Shining through a Wall” from the quantum oscillation of optical photons into “Weakly Interacting Sub-eV Particles”, like axion or axion-like particles (ALPs), in a 9 T transverse magnetic field over the unprecedented length of
2
×
14.3
m. No excess of events has been detected over the background. The di-photon couplings of possible new light scalar and pseudo-scalar particles can be constrained in the massless limit to be less than
8.0
×
10
-
8
GeV
-
1
. These results are very close to the most stringent laboratory constraints obtained for the coupling of ALPs to two photons. Plans for further improving the sensitivity of the OSQAR experiment are presented.
Hybrid Magnets-Past, Present, and Future Pugnat, P.; Schneider-Muntau, H. J.
IEEE transactions on applied superconductivity,
06/2014, Volume:
24, Issue:
3
Journal Article, Conference Proceeding
Peer reviewed
Since the pioneering work of Wood and Montgomery in 1965 at the Francis Bitter Laboratory, hybrid magnets are still the optimal approach of producing the highest continuous magnetic fields with ...limited electrical power consumption. They consist of a large-bore superconducting magnet surrounding a small-bore, high-power-density resistive magnet. Hybrid magnets can generate fields well above those possible today with a purely superconducting magnet and can allow substantial savings in conductor volume and/or power consumption compared to purely resistive magnets. In this article, progress achieved in the design and construction of hybrid magnets will be reviewed. Perspectives for the construction of magnets producing fields above 60 T will be presented highlighting key challenges that need to be solved.
Current technical superconductors, such as Nb 3 Sn, are limited to fields around 20 T by their intrinsic material properties. Generating significantly stronger magnetic fields can only be done by ...using resistive magnets, or by combining superconducting and resistive magnets (hybrid magnets), at the expense of large power consumption and operating cost. A CEA-CNRS French collaboration is currently developing a new hybrid magnet, which combines a resistive insert composed of Bitter and polyhelix coils and a new large-bore superconductor outsert to produce an overall continuous magnetic field of more than 42 T in a 34-mm warm aperture. Based on the novel development of a NbTi/Rutherford cable on conduit (RCOCC) cooled down to 1.8 K by means of the bath of superfluid helium at atmospheric pressure, the superconducting coil aims to produce a continuous magnetic field of 8.5 T in a 1.1-m cold bore diameter. This paper summarizes the results of the mechanical behavior study of the cold mass cooled from room to operating temperature and Lorentz forces at operating temperature. Computations have been performed in 2-D axisymmetry and 3-D, to take into account the axisymmetric discontinuous distribution of the tie rods.
Hybrid magnets enable to achieve very high magnetic fields by combining resistive insert magnets with a large bore superconducting outer coil. In order to reduce the electromagnetic coupling between ...the coils, we introduce an eddy-current shield between the resistive and superconducting magnet. This additional shield is responsible for heat loads. To limit the degradation of the thermal behavior of the cold mass, an innovative support ferrule has been designed. It allows rigid connection of the eddy-current shield to the magnet structure. In this paper, the worst magnetic failure scenario is identified and modeled. It results in large transient forces applying to the structure. Transient mechanical analysis of the hybrid magnet structure featuring innovative support ferrule is presented. Simulations show that the proposed configuration leads to lower mechanical stresses than a configuration featuring a suspended shield.
Based on a close collaboration between CEA and CNRS, a new hybrid magnet is being built at LNCMI-Grenoble. By combining a resistive insert, which is made of Bitter and polyhelix coils, with a large ...bore superconducting outsert, an overall continuous magnetic field of at least 43 T will be produced in a 34-mm warm bore aperture. The superconducting coil relies on the novel development of a Nb-Ti/Cu Rutherford cable-on-conduit conductor cooled down to 1.8 K by a bath of superfluid helium at atmospheric pressure and will produce a nominal magnetic field of 8.5 T in a 1.1-m cold bore diameter. After thorough reviews of the hybrid magnet design, which have anticipated possible upgrades of the maximum magnetic field produced, the project has entered in its production phase. The status and the next steps of the project will be reviewed highlighting the remaining technical challenges.
The regular lattice of the large Hadron collider (LHC) will make use of more than 1600 main magnets and about 7600 corrector magnets, all superconducting and working in pressurized superfluid helium ...bath. This complex magnet system will fill more than 20 km of the LHC underground tunnel. In this paper an overview of the cold test program and quality assurance plan to qualify all LHC superconducting magnets will be presented. The quench training performance of more than 1100 LHC main dipoles and about 300 main quadrupoles, cold tested to date, will be reviewed. From these results an estimate of the number of quenches that will be required to start operation of the whole machine at nominal energy will be discussed. The energy level at which the machine could be operated at the early phase of the commissioning without being disturbed by training quenches will be addressed. The LHC magnet program required the development of many new tools and techniques for the testing of superconducting magnet coils, magnet protection systems, cryogenics, and instrumentation. This paper will also present a summary of this development work and the results achieved.
To produce a continuous magnetic field of at least 8.5 T in a 1.1 m cold bore diameter, the superconducting outsert of the Grenoble Hybrid magnet is based on the novel development of a Nb-Ti/Cu ...Rutherford Cable On Conduit Conductor (RCOCC) cooled to 1.8 K by a bath of superfluid helium pressurized at atmospheric pressure. The main results of the conductor studies and development are presented after a brief introduction to the specificity of hybrid magnets, namely the electromagnetic couplings between resistive and superconducting coils. Results obtained with short samples of conductor are reviewed including the measurements of the elastic limit, AC losses, stability and critical current. The final specification of the RCOCC is presented highlighting the proposed method for the industrialization of the insertion process of the Rutherford cable on the hollow Cu-Ag stabilizer as well as its validation phase on short samples.
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