The Muon Ionization Cooling Experiment (MICE) will be the first experiment to demonstrate muon ionization cooling in the momentum range of 140–240MeV/c. The experiment is a single-particle experiment ...where the input and output beam emittances are constructed from an ensemble of selected single-muon candidates. The fiber trackers are placed in a solenoidal field of 4T (one before and one after the cooling channel) to measure the muon 4-momentum and provide the basic information for determining the emittances. This paper gives a brief overview of MICE and then describes the details of the fiber tracker assemblies, the unique construction technique used (which for the first time used 350μm diameter scintillating fiber), the readout electronics and performance with respect to light yield, hit resolution and tracking efficiency as measured in a recent cosmic-ray test of the two final tracker systems.
•Model of 3D temperature profiles and pressure drop in concentric three-phase HTS power cables.•Consideration of AC losses in the phases in addition to external thermal loads.•Modelling and ...monitoring of the operating range, based on parameters measured at the cable end.•Application study for increasing the length of HTS power cables.
To meet the increasing power demand in cities under the spatial constraints for cable channels, the application of high temperature superconducting (HTS) cables cooled with liquid nitrogen offers an increasingly attractive alternative to conventional cable solutions. This paper presents a differential equation model for three-phase concentric HTS cables, describing the temperature distribution in the various cable layers and in the liquid nitrogen flow. The design of the 1km long AmpaCity cable is used as a reference, which presently is the longest HTS cable installation in the world. The model considers the AC losses in the superconducting phases in addition to the external thermal load, as well as pressure losses in the coolant flow. The integrity of the algorithm is verified through energy conservation, yielding negligible numerical solver errors. The model is then applied to the operation of the AmpaCity cable. The monitoring of its operating range is explained, based on electrical and coolant properties measured at the cable end. The final application study shows options for extending the cable length up to factor five, using a second cooling unit in combination with a mixed coolant.
Pelvic obliquity is a common finding in adolescents with cerebral palsy, however, there is little agreement on its measurement or relationship with hip development at different gross motor function ...classification system (GMFCS) levels. The purpose of this investigation was to study these issues in a large, population-based cohort of adolescents with cerebral palsy at transition into adult services. The cohort were a subset of a three year birth cohort (n = 98, 65M: 33F, with a mean age of 18.8 years (14.8 to 23.63) at their last radiological review) with the common features of a migration percentage greater than 30% and a history of adductor release surgery. Different radiological methods of measuring pelvic obliquity were investigated in 40 patients and the angle between the acetabular tear drops (ITDL) and the horizontal reference frame of the radiograph was found to be reliable, with good face validity. This was selected for further study in all 98 patients. The median pelvic obliquity was 4° (interquartile range 2° to 8°). There was a strong correlation between hip morphology and the presence of pelvic obliquity (effect of ITDL on Sharpe's angle in the higher hip; rho 7.20 (5% confidence interval 5.59 to 8.81, p < 0.001). This was particularly true in non-ambulant adolescents (GMFCS IV and V) with severe pelvic obliquity, but was also easily detectable and clinically relevant in ambulant adolescents with mild pelvic obliquity. The identification of pelvic obliquity and its management deserves closer scrutiny in children and adolescents with cerebral palsy.
We wished to examine the effectiveness of tibial lengthening using a two ring Ilizarov frame in skeletally immature patients. This is a potentially biomechanically unstable construct which risks the ...loss of axial control.
We retrospectively reviewed a consecutive series of 24 boys and 26 girls, with a mean age of 8.6 years (4 to 14), who underwent 52 tibial lengthening procedures with a mean follow-up of 4.3 years (4.0 to 16.9). Tibial alignment was measured before and after treatment using joint orientation lines from the knee and a calculation of the oblique plane axis.
The mean percentage length gain was 20% (13 to 31) with a mean bone-healing index (BHI) of 34 days per centimetre (20 to 54). Age at surgery and location of the osteotomy site showed a strong relationship as the location of the osteotomy migrated more proximally with age. However, no significant correlation was found between BHI and the position of the osteotomy. The coronal and sagittal joint orientation of the lengthened tibias were within the normal range in 67% and 92% of cases, respectively. The oblique plane angulation calculation revealed a statistically significant change pre- to post-operatively in both magnitude (p < 0.05) and direction (p < 0.01), but without clinical consequence. The majority of complications were minor (n = 40 in 27 patients; 1.48 complications per segment lengthened) with no residual disability reported.
Two-ring tibial lengthening is effective in maintaining segmental alignment, efficient in callous production and relatively comfortable for the patient with few significant complications. Cite this article: Bone Joint J 2016;98-B:1276-82.
Abstract
Purpose
The treatment of early onset scoliosis continues to be a major challenge, even when using motorized growth-sparing implants. We report on 30 cases operated on with magnetically ...controlled growing rods (MCGRs) at our institution, analyzing radiological parameters and complications, comparing our results with the literature and presenting a special implant fixation technique. A separate focus highlights the challenges of conversion from previous non-motorized implants.
Methods
Consecutive case series. The nature and effects of complications were recorded for all patients. Radiographic evaluations were performed for patients with a minimum follow-up of two years. Separate analyses were carried out for patients who were previously treated with non-motorized growth-sparing implants
Results
There were 12 documented complications in 11/30 (37%) patients leading to 13 unplanned returns to the operating room. In all, 18/30 patients had a minimum follow-up of two years. Major curve and main kyphosis, as well as T1 to T12 and T1 to S1 distances significantly improved with MCGR implantation, however, less in patients converted from previous growth-sparing surgical treatment. While the achieved correction of the major curve was maintained, there was a loss of kyphosis correction with subsequent implant lengthening. Gain in implant length decreased with increasing number of extensions.
Conclusion
Despite improved patient's comfort, MCGR show a considerable complication rate. Coronal plane deformities can be well controlled, but diminished implant lengthening is already apparent within two years after MCGR implantation. Central databases should help to clarify unresolved aspects and optimize the treatment of these young patients.
Level of Evidence
IV
The Muon Ionization Cooling Experiment (MICE) collaboration seeks to demonstrate the feasibility of ionization cooling, the technique by which it is proposed to cool the muon beam at a future ...neutrino factory or muon collider. The emittance is measured from an ensemble of muons assembled from those that pass through the experiment. A pure muon ensemble is selected using a particle-identification system that can reject efficiently both pions and electrons. The position and momentum of each muon are measured using a high-precision scintillating-fibre tracker in a 4 T solenoidal magnetic field. This paper presents the techniques used to reconstruct the phase-space distributions in the upstream tracking detector and reports the first particle-by-particle measurement of the emittance of the MICE Muon Beam as a function of muon-beam momentum.
The test facility PICARD, which stands for Pressure Increase in Cryostats and Analysis of Relief Devices, has been designed and constructed for cryogenic safety experiments. With a cryogenic liquid ...volume of 100 L, a nominal design pressure of 16 bar(g) and the capacity of measuring helium mass flow rates through safety relief devices up to 4 kg/s, the test facility allows the systematic investigation of hazardous incidents in cryostats under realistic conditions. In the course of experiments, the insulating vacuum is vented with atmospheric air or gaseous nitrogen at ambient temperature under variation of the venting diameter, the thermal insulation, the cryogenic fluid, the liquid level and the set pressure in order to analyze the impact on the heat flux and hence on the process dynamics. A special focus will be on the occurrence and implications of two-phase flow during expansion and on measuring the flow coefficients of safety devices at cryogenic temperatures. This paper describes the commissioning and the general performance of the test facility at liquid helium temperatures. Furthermore, the results of first venting experiments are presented.
The Physics Program of MICE Step IV Heidt, C.
Nuclear and particle physics proceedings,
April-June 2016, 2016-04-00, Letnik:
273-275
Journal Article
Recenzirano
Odprti dostop
The Muon Ionization Cooling Experiment (MICE) is progressing towards a demonstration of the cooling technology required for the Neutrino Factory and the Muon Collider. MICE Step IV will allow the ...cooling properties of liquid hydrogen and lithium hydride to be studied in detail and provide the first opportunity to observe the reduction of normalized transverse emittance using ionization cooling. Absorbers sited within a superconducting focus-coil magnet will cause the muon beam to lose energy. The muon-beam phase space upstream and downstream of the absorber/focus-coil module will be measured using two solenoidal spectrometers. After a brief summary of the status of the experiment, the physics program of Step IV is described.
PDF
