This paper presents the lessons learned from tests of first module of superconducting cryogenic bypass line (BPL), a part of the international Facility for Antiproton and Ion Research (FAIR) SIS100 cryogenic system, currently under construction in Darmstadt, Germany. Design, manufacturing, and installation of the superconducting cryogenic bypass line is a part of a Polish in-kind contribution to the FAIR project, realized by the Wroclaw University of Science and Technology. The main goal of the tests was to check the superconducting, Nuclotron type busbar system containing four pairs of busbars, transferring 13.2 kA pulsing current with the ramp rate of 28 kA/s. The mechanical stability of the busbars, especially at the connection region, was investigated with the use of vibration sensors and cameras located inside the vacuum space. The tests revealed insufficient mechanical stability of the busbars in the connection area due to pulsing Lorentz forces, and necessity of additional supports and clamps. Results of the tests were presented and discussed. The conclusions can be significant not only for the bypass line design, but also for design of the busbar connections in the superconducting magnets.

This paper presents the selected aspects of a superconducting cryogenic bypass line (BPL) design, a part of the international Facility for Antiproton and Ion Research (FAIR) SIS100 cryogenic system, currently under construction in Darmstadt, Germany. Design, manufacturing, and installation of the superconducting cryogenic bypass line is a part of a Polish in-kind contribution to the FAIR project, realized by the Wroclaw University of Science and Technology. The BPL is dedicated to transferring liquid helium and AC electric current between SIS100 arc sections and superconducting quadrupole magnets located in warm straight sections of the synchrotron. A main innovative feature of the cryogenic bypass line is transferring the electric current and liquid helium in one vacuum vessel, while in other similar projects, namely, the Large Hadron Collider at CERN (CH) or the Tevatron at FermiLab (USA), those functions are separated. The coexistence of superconducting busbars and liquid helium process pipes in one limited space, as well as numerous additional functional and technical requirements, was a source of the serious design and production challenges described in the paper, including two designs of the internal suspension system based on steel rods and aramid cables.

The superconducting, heavy ion synchrotron SIS100 is the core of the new FAIR facility at GSI, Darmstadt, Germany. Its unique design is dedicated to the acceleration of intermediate charge state heavy ions. Several new technical approaches assure the stabilization of the vacuum dynamics and the minimization of charge related beam loss. Beside high intensity heavy ions, SIS100 will accelerate all ions from Protons to Uranium, and in spite of the fact that superconducting magnets are used, SIS100 shall be as flexible in ramping and cycling as a normal conducting synchrotron.

FAIR, which is currently being built at GSI, will provide particle beams with unprecedented intensity and quality. The facility's diversity makes it unique: ions of all natural elements of the periodic table as well as antiprotons can be accelerated. Hence the accelerators and the experimental infrastructure have to be extremely flexible in the adaptation to various operating schemes. The main accelerator, that will be realized within the starting phase of FAIR, is the SIS100 (SchwerlonenSychrotron 100 Tm). The superconducting magnets of SIS100 will to be hardly not to fast-ramped for several hours, which causes variations in the 4.5K heat load by factor 4. The larger cold mass and the higher liquid helium inventory is necessary for the Super-FRS (Superconducting FRagment Seperator), which will be supplied from the same cryo plant as SIS100.

In order to test the fast-ramped superconducting magnets for FAIR ( Facility for Antiproton and Ion Research), a cryogenic test facility was designed, constructed, installed and brought into operation at GSI. The overall capacity of the cryo plant is about 1.5 kW @ 4.4 K equivalent and can be distributed to four test benches individually. In total 108 dipoles for the SIS100 will be tested at cold. The capacity of the cryogenic system is designed in order to simultaneously cool down one magnet while the other one is operated at cold state for the measurements. The other two test benches serve for warming up and for magnet exchange, respectively. Like this, one magnet per week can be tested. Beyond the dipoles, the high flexibility of the setup allows also the testing of other FAIR magnets, like the SIS100 quadrupole modules or the operation of a string configuration. The design of the cryogenic infrastructure, including an advanced feed box and magnet support system, will be presented. Operating experience from the first 8000 h of operating and serving different tests and an overview of the upcoming serial test time schedule will be given.

The heavy-ion synchrotron of the planned FAIR accelerator complex, SIS100, consists of 300 fast-ramped superconducting magnet units which are cooled with liquid helium at 4.5 K. The cooling principle is based on 2-phase forced flow being sub-cooled at the inlet.Each dipole and quadrupole unit will have an individual cooling channel. These channels are arranged in parallel and are attached to a common supply and a common return header. The heat loads and the hydraulic behaviour of dipole and quadrupole units differ significantly. In order to balance the different cooling channels and to adapt the cooling power to the various magnet ramping cycles, a heater-capillary combination will be utilised. This combination acts as a thermo-hydraulic "valve" and reduces the helium mass flow.Different capillary geometries and helium inlet properties (sub-cooling, void fraction and pressure) are investigated. A restriction of the mass flow sufficient for the SIS100 demands can be observed. The helium mass flow can be continuously regulated, from 100 % up to about 50 %, by varying the heating power. Along with the reduction of the inlet pressure, the mass flow can be controlled down to about 30 %. The SIS100 cooling scheme, the test setup, the performed measurements and the results will be described and compared to a theoretical model, which is based on empirical equations.

SIS100 is the main accelerator of the FAIR project. It is a worldwide unique heavy ion synchrotron dedicated to accelerate highest intensities of intermediate charge state heavy ionand proton beams up to 100 Tm. From the technical point of view, most challenging issues are the fast ramped superconducting magnets and the acceleration of intense, intermediate charge state heavy ions beams. The latter required a unique lattice design (charge separator lattice) in combination with an ultrahigh vacuum system based on distributed cryo-pumping with actively cooled magnet chambers, adsorption pumps and dedicated cryo-catchers for local suppression of gas desorption [1].

In the coming years a new international accelerator Facility for Antiproton and Ion Research (FAIR), one of the largest research projects worldwide, will be build close to Darmstadt in Germany. FAIR will provide antiproton and ion beams with unprecedented intensity and quality. One of its major accelerators will be a synchrotron called SIS100 having a circumference of about 1100 meters. The SIS100 tunnel will house a complex cryogenic system supplying up to 20 kW cooling capacity @ 4.5 K to about 300 superconducting fast ramped magnets and other physics equipment. The planned SIS100 local cryogenic system can be principally divided into three sections each fed from a separate Feed Box. Every Feed Box supplies 4.5 K helium for magnet, vacuum chamber, cryo collimator, current lead and bus-bar cooling as well as 50 K helium for the current lead and thermal shield cooling, independently to two sixth of the ring. Each sixth of the ring, so called sextant, consists of a cold arc and a straight warm section. By-pass Lines circumvent the straight warm sections of the sextants, where warm equipment (e.g. normal conducting cavities and magnets) is located. Between the warm equipment, are superconducting magnets located which also need to be supplied from the By-pass Lines with helium and cold electrical connections. The By-pass Lines are Polish in-kind contribution, coordinated by the Jagiellonian University of Krakow and will be designed, manufactured and commissioned by the Wroclaw University of Technology. In this paper the SIS100 local cryogenic system will be described with focus on the By-pass Lines and on magnet cooling including the balancing of differences between dipole and quadrupole circuits and the coping with dynamic loads.

As a result of the foreseen increase in the luminosity of the Large Hadron Collider, the discrimination between the collision products and possible magnet quench-provoking beam losses of the primary proton beams is becoming more critical for safe accelerator operation. We report the results of ongoing research efforts targeting the upgrading of the monitoring system by exploiting Beam Loss Monitor detectors based on semiconductors located as close as possible to the superconducting coils of the triplet magnets. In practice, this means that the detectors will have to be immersed in superfluid helium inside the cold mass and operate at 1.9K. Additionally, the monitoring system is expected to survive 20 years of LHC operation, resulting in an estimated radiation fluence of 1×1016 proton/cm2, which corresponds to a dose of about 2MGy. In this study, we monitored the signal degradation during the in situ irradiation when silicon and single-crystal diamond detectors were situated in the liquid/superfluid helium and the dependences of the collected charge on fluence and bias voltage were obtained. It is shown that diamond and silicon detectors can operate at 1.9K after 1×1016p/cm2 irradiation required for application as BLMs, while the rate of the signal degradation was larger in silicon detectors than in the diamond ones. For Si detectors this rate was controlled mainly by the operational mode, being larger at forward bias voltage.

A large fraction of the program to upgrade the existing heavy ion synchrotron SIS18 as injector for the FAIR synchrotron SIS100 has been successfully completed. With the achieved technical status, a major increase of the accelerated number of heavy ions could be reached. The now available performance especially demonstrates the feasibility of high intensity beams of medium charge state heavy ions with a sufficient control of the dynamic vacuum and connected charge exchange loss. Two further upgrade measures, the installation of additional magnetic alloy (MA) acceleration cavities and the exchange of the main dipole power converter, are presently being implemented. For the FAIR synchrotron SIS100, the procurement of all major components with long production times has been started. With the delivery and testing of several pre-series components, the phase of outstanding technical reserach and developments could be completed and the readiness for series production achieved.

High thermal resistances exist at ultra-low temperatures for solid-solid interfaces. This is especially true for pressed metal-sapphire joints, where the heat is transferred by phonons only. For such pressed joints it is difficult to achieve good physical, i.e. thermal contacts due to surface irregularities in the microscopic or larger scale. Applying ductile indium as an intermediate layer reduces the thermal resistance of such contacts. This could be proven by measurements of several researchers. However, the majority of the measurements were performed at temperatures higher than 1 K. Consequently, it is difficult to predict the thermal resistance of pressed metal-sapphire joints at temperatures below 1 K.In this paper the thermal resistances across four different copper-sapphire-copper sandwiches are presented in a temperature range between 30 mK and 100 mK. The investigated sandwiches feature either rough or polished sapphire discs (empty set 20 mm x 1.5 mm) to investigate the phonon scattering at the boundaries. All sandwiches apply indium foils as intermediate layers on both sides of the sapphire. Additionally to the indium foils, thin indium films are vapour deposited onto both sides of one rough and one polished sapphire in order to improve the contact to the sapphire.Significantly different thermal resistances have been found amongst the investigated sandwiches. The lowest total thermal resistivity (roughly 26 cm(2) K-4/W at 30 mK helium temperature) is achieved across a sandwich consisting of a polished sapphire with indium vapour deposition. The thermal boundary resistance between indium and sapphire is estimated from the total thermal resistivity by assuming the scattering at only one boundary, which is the warm sapphire boundary where phonons impinge, and taking the scattering in the sapphire bulk into account. The so derived thermal boundary resistance agrees at low temperatures very well with the acoustic mismatch theory. (C) 2014 Elsevier Ltd. All rights reserved.

It is expected that the luminosity of the Large Hadron Collider (LHC) will be bounded in the future by the beam loss limits of the superconducting magnets. To protect the superconducting magnets of the high luminosity insertions an optimal detection of the energy deposition by the shower of beam particles is necessary. Therefore beam Loss Monitors (BLM) need to be placed close to the particle impact location in the cold mass of the magnets where they should operate in superfluid helium at 1.9 Kelvin. To choose optimal detectors n-type silicon wafers have been examined at superfluid helium temperature whilst under irradiation from a high intensity proton beam. The radiation hardness and leakage current of these detectors were found to be significantly improved at 1.9 Kelvin when compared to their operation at room temperature.

Measurements of the temperature dependence of the charge carrier mobility in single-crystal chemical vapour deposition diamond using the transient current technique are presented in a temperature range from 2 K to room temperature. An α-source is used to create free charge carriers in the diamond bulk. The evolution of the current signal induced by their drift under the influence of an externally applied field is studied as a function of the temperature and the electric field strength. The electric field strength is varied by a factor of 30. The measurements are used to extract the transit time, the drift velocity, the saturation velocity, and the low-field mobility in terms of which the results are interpreted. Three samples have been studied which show the same behaviour. For holes, the mobility increases with decreasing temperature due to the acoustic phonon scattering, but it saturates for ultra-cold temperatures. The low-field mobility for holes at room temperature is measured as μ0h(295K)=(2534±20) cm2/Vs saturating against μ0h(→2K)=(11130±120) cm2/Vs. For electrons, only a lower limit on the low-field mobility can be given. It is measured as μ¯0e(295K)=(1802±14) cm2/Vs saturating against μ¯0e(→2K)=(3058±27) cm2/Vs. The electron transit time at low fields shows a different behaviour than the hole transit time and is not following the expected behaviour. This is likely to be caused by a high temperature valley re-population effect.

At the triplet magnets, close to the interaction regions of the Large Hadron Collider (LHC), the current Beam Loss Monitoring (BLM) system is sensitive to the debris from the collision points. For future beams, with higher energy and intensity the expected increase in luminosity implicate an increase of the debris from interaction products covering the quench-provoking beam losses from the primary proton beams. The investigated option is to locate the detectors as close as possible to the superconducting coil, where the signal ratio of both is optimal. Therefore the detectors have to be located inside the cold mass of the superconducting magnets in superfluid helium at 1.9 Kelvin. Past measurements have shown that a liquid helium ionisation chamber, diamond and silicon detectors are promising candidates for cryogenic beam loss monitors. The carrier parameter, drift velocity, and the leakage current changes will be shown as a function of temperature. New high irradiation test beam measurements at room temperature and 1.9 Kelvin will reveal the radiation tolerance of the different detectors. Presented at the IBIC 2013 conference – Oxford/UK – 16-19 September 2013 Geneva, Switzerland December, 2013 OPERATION OF SILICON, DIAMOND AND LIQUID HELIUM DETECTORS IN THE RANGE OF ROOM TEMPERATURE TO 1.9 K AND AFTER AN IRRADIATION DOSE OF SEVERAL MEGA GRAY ∗ C. Kurfuerst† , M. R. Bartosik, B. Dehning, T. Eisel, M. Sapinski, CERN, Geneva, Switzerland, V. Eremin, IOFFE, St. Petersburg, Russian Federation Abstract At the triplet magnets, close to the interaction regions of the Large Hadron Collider (LHC), the current Beam Loss Monitoring (BLM) system is sensitive to the debris from the collision points. For future beams, with higher energy and intensity the expected increase in luminosity implicate an increase of the debris from interaction products covering the quench-provoking beam losses from the primary proton beams. The investigated option is to locate the detectors as close as possible to the superconducting coil, where the signal ratio of both is optimal. Therefore the detectors have to be located inside the cold mass of the superconducting magnets in superfluid helium at 1.9 Kelvin. Past measurements have shown that a liquid helium ionisation chamber, diamond and silicon detectors are promising candidates for cryogenic beam loss monitors. The carrier parameter, drift velocity, and the leakage current changes will be shown as a function of temperature. New high irradiation test beam measurements at room temperature and 1.9 Kelvin will reveal the radiation tolerance of the different detectors.At the triplet magnets, close to the interaction regions of the Large Hadron Collider (LHC), the current Beam Loss Monitoring (BLM) system is sensitive to the debris from the collision points. For future beams, with higher energy and intensity the expected increase in luminosity implicate an increase of the debris from interaction products covering the quench-provoking beam losses from the primary proton beams. The investigated option is to locate the detectors as close as possible to the superconducting coil, where the signal ratio of both is optimal. Therefore the detectors have to be located inside the cold mass of the superconducting magnets in superfluid helium at 1.9 Kelvin. Past measurements have shown that a liquid helium ionisation chamber, diamond and silicon detectors are promising candidates for cryogenic beam loss monitors. The carrier parameter, drift velocity, and the leakage current changes will be shown as a function of temperature. New high irradiation test beam measurements at room temperature and 1.9 Kelvin will reveal the radiation tolerance of the different detectors.

At the triplet magnets, close to the interaction regions of the LHC, the current Beam Loss Monitoring (BLM) system is very sensitive to the debris from the collisions. For future beams with higher energy and higher luminosity this will lead to a situation in which the BLM system can no longer distinguish between these interaction products and quench-provoking beam losses from the primary proton beams. The solution investigated is to locate the detectors as close as possible to the superconducting coil, i.e. the element to be protected. This means putting detectors inside the cold mass of the superconducting magnets at 1.9 K. As possible candidates for such loss monitors, diamond, silicon and a liquid helium chamber have been tested in a proton beam at liquid helium temperatures. The initial promising results from these tests will be presented and discussed in this contribution.