Construction of a new primary beam line, called the B-line, started in 2013 at the J-PARC Hadron Experimental Facility. The B-line is branched at the middle of an existing primary proton beam line ...(A-line) in the beam switching yard (SY), which is the connecting tunnel between the Main Ring (MR) and the Hadron experimental hall (HD-hall). At the branching point, about 0.1% of the primary beam is kicked off at 5 degrees using a Lanbertson magnet and two septum magnets. The Lambertson magnet has a field free hole in its yoke. The proton beam that goes through a field region is separated from the A-line, and it is extracted to the B-line. The rest of the beam that goes through the field free hole is transported through the existing primary beam line. Since a significant beam loss as much as 420 W occurs at the edge of field free hole, the magnets near the Lambertson magnet are operated under a very high radioactive environment. We have developed a "mini-chimney system" regarding easy maintenance of those magnets. The mini-chimney means a vertical tower of approximately 1m in height. The tower is comprised of water pipes, power electrodes, and signal cables for safety interlock. Those can be easily connected and disconnected at the top of chimney on the ceiling iron shields. In this paper we summarize the maintenance scheme developed for the B-line, as well as the design of B-line.In May 2020, the first proton beam was successfully extracted to the B-line by means of the Lambertson and the septum magnets. Up to now, the 10 10 protons per 5.2 sec accelerator cycle shot have been available.
Abstract
J-PARC Main Ring (MR) delivers a slow extracted 30 GeV proton beam to the Hadron Experimental Facility using third-order resonance. One of the critical properties required for the proton ...beam is the flatness of the time structure of the extracted beam (spill structure). We performed a simple beam simulation of the MR slow beam extraction to investigate the effect of the current ripples of the main magnet power supplies on the beam spill structure. In addition, we investigated in the simulation the effects of the feedback control system on the betatron tune using fast Q magnets and the transverse RF system to improve the spill structure. The simulation qualitatively reproduced the measured spill structures. Now the attempts to optimize their parameters for better spill structure are ongoing.
Slow extraction from the J-PARC main ring using a dynamic bump Tomizawa, M.; Arakaki, Y.; Kimura, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2018, Letnik:
902
Journal Article
Recenzirano
A dynamic bump under the achromatic condition has been applied for third integer slow extraction from the Japan Proton Accelerator Research Complex main ring. This dynamic bump scheme has drastically ...reduced beam loss rate for slow extraction compared to that for a fixed bump mode. The low beam loss rate for slow extraction has been retained for high power operations. A beam power of 41−44.4 kW was achieved for physics runs using the slow extraction by applying the dynamic bump scheme. The beam profile measured just upstream of the target indicates that the beam spot at the target does not travel over the entire extraction time. This behavior is advantageous for experimental data acquisition.
A 30 GeV proton beam accelerated in the J-PARC Main Ring (MR) is slowly extracted by the third integer resonant extraction and delivered to the hadron experimental facility. A dynamic bump scheme ...under achromatic condition drastically reduces beam hit rate on the septa devices, and we have attained 51 kW SX operation at 5.2 s cycle with high slow extraction efficiency of 99.5%. A spill duty factor indicating a uniformity of the time structure of the extracted beam is typically 50%. The current SX performance and future plans for improvements will be presented.
OBJECTIVES: Multiple myeloma (MM) is a disease of the bone marrow characterized by the uncontrolled proliferation of immunoglobulin-producing plasma cells. It accounts for 1,2% of all cancers ...diagnosed in Italy and is associated with a significant burden of illness. Daratumumab monotherapy was recently approved for the treatment of adults with relapsed and refractory MM, whose prior therapy included a proteasome inhibitor and an immunomodulatory agent, and who have demonstrated progression on the last therapy. The aim of the study is to assess the cost-effectiveness of daratumumab in this setting compared to pomalidomide and low-dosed dexamethasone (LDD) in Italy. METHODS: The study is based on a survival partition model comparing treatment costs and outcomes from the Italian NHS perspective. The model was adapted using trial data, literature and local sources. Drug list prices and national tariffs were used to estimate treatment costs over a 10 year-timeframe with a 3,5% discount rate. Treatments were compared by incremental cost-effectiveness ratio (ICER) per life year (LY) gained. As Italy does not have a formalized cost-effectiveness threshold, a literature value of 60f k/LY was adopted (Messori, 2004). RESULTS: The results demonstrate the cost-effectiveness of daratumumab's new immunotherapeutic approach compared to pomalidomide and LDD in the target population, providing an additional 1.1 LY with incremental direct costs of 36,681f.The analysis established an ICER of 34,1516 per LY gained versus pomalidomide and LDD, falling within the acceptability threshold of 606k/LY.The results were confirmed through deterministic and probability sensitivity analyses, as in 94% (DSA) and 95% (PSA) of cases, the ICER lies within the above threshold. CONCLUSIONS: This study proves that daratumumab is a cost-effective therapy for the treatment of MM in the Italian NHS, compared to SOC for patients who have received ≥2 prior lines of therapy, including a PI or an IMiD, or who were double refractory to both.
The invariant mass spectra of e+e- pairs produced in 12 GeV proton-induced nuclear reactions are measured at the KEK Proton Synchrotron. On the low-mass side of the meson peak, a significant ...enhancement over the known hadronic sources has been observed. The mass spectra, including the excess, are well reproduced by a model that takes into account the density dependence of the vector meson mass modification, as theoretically predicted.
Invariant mass spectra of e(+) e(-) pairs have been measured in 12 GeV p + A reactions to detect possible in-medium modification of vector mesons. Copper and carbon targets are used to study the ...nuclear-size dependence of e(+) e(-) invariant mass distributions. A significant excess on the low-mass side of the phi meson peak is observed in the low betagamma(= beta/square root(1-beta(2))) region of phi mesons (betagamma < 1.25) with copper targets. However, in the high betagamma region (betagamma > 1.25), spectral shapes of phi mesons are well described by the Breit-Wigner shape when experimental effects are considered. Thus, in addition to our earlier publications on rho/omega modification, this study has experimentally verified vector meson mass modification at normal nuclear density.
In the main ring (MR) of the Japan Proton Accelerator Research Complex (J-PARC), the power supplies of magnets induce large ripples in the betatron tunes. The tune ripples degrade the quality of the ...beam spill on the slowly extracted beam. To improve the spill quality, the J-PARC MR employed a feedback system using a beam spill monitor; however, the existing system could not correct the beam spills suitably, since the tune ripples were too large. We developed a new correction system using the information of magnet currents as an input of the correction. The new system consists of current monitors and a corrector quadrupole, and it allows us to correct the ripples in real time. Using this system, we successfully corrected the tune ripples for the first time in the J-PARC MR. The correction system improved the spill quality from 3% (without any correction) to 30% (with the new correction), whereas the quality using the present feedback system is 17.4%.
After the radioactive material leak accident at the J-PARC hadron experimental facility on May 23, 2013, we designed a new production target, which is capable of a primary proton beam with the energy ...of 30 GeV and power of 50 kW. It is made of gold and cooled by water through a copper block. For the countermeasures of the recurrence of the accident, the target is enclosed by an airtight chamber and helium gas is circulated to monitor the target soundness. In this paper, technical details of the new target design are presented.
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