Tetsushi Shimogawa
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View article: Development of the beam separation test device to evaluate the electric field of non-destructive electrostatic septum
Development of the beam separation test device to evaluate the electric field of non-destructive electrostatic septum Open
Slow extraction is utilized for various nuclear and particle physics experiments and radiology in synchrotrons. A beam loss at a septum electrode induces equipment activation and damage. We have been developing a non-destructive electrosta…
View article: Proposal of Non-destructive Device for Slow Extraction
Proposal of Non-destructive Device for Slow Extraction Open
View article: J-PARC Main Ring Upgrade toward High Repetition Rate Operation
J-PARC Main Ring Upgrade toward High Repetition Rate Operation Open
View article: Accelerator design for 1.3-MW beam power operation of the J-PARC Main Ring
Accelerator design for 1.3-MW beam power operation of the J-PARC Main Ring Open
The J-PARC Main Ring (MR) has supplied the high-intensity proton beam for the T2K long-baseline neutrino experiment since 2010. The present beam power is 510 kW and the total number of protons on the target reaches $3.64\times10^{21}$. To …
View article: Compensations of Third-Order Resonances in J-PARC MR
Compensations of Third-Order Resonances in J-PARC MR Open
The main ring synchrotron (MR) of the Japan Proton Accelerator Research Complex (J-PARC) provides high-power proton beams for the neutrino and hadron experiments. In the fast extraction (FX) operation, the beams are injected with the energ…
View article: Pulse shape discrimination of photons and neutrons in the energy range of 0.1 – 2 GeV with the KOTO un-doped CsI calorimeter
Pulse shape discrimination of photons and neutrons in the energy range of 0.1 – 2 GeV with the KOTO un-doped CsI calorimeter Open
View article: First search for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>K</mml:mi><mml:mi>L</mml:mi></mml:msub><mml:mo stretchy="false">→</mml:mo><mml:msup><mml:mi>π</mml:mi><mml:mn>0</mml:mn></mml:msup><mml:mi>γ</mml:mi></mml:math>
First search for Open
We report the first search for the $K_L \\to \\pi^0 \\gamma$ decay, which is\nforbidden by Lorentz invariance, using the data from 2016 to 2018 at the J-PARC\nKOTO experiment. With a single event sensitivity of $(7.1\\pm 0.3_{\\rm stat.}\n…
View article: CsI calorimeter for the J-PARC KOTO experiment
CsI calorimeter for the J-PARC KOTO experiment Open
View article: Current status of slow extraction from J-PARC Main Ring
Current status of slow extraction from J-PARC Main Ring Open
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 redu…
View article: Studies on coherent multi-bunch tune shifts with different bunch spacing at the J-PARC Main Ring
Studies on coherent multi-bunch tune shifts with different bunch spacing at the J-PARC Main Ring Open
At a high-power proton synchrotron, betatron tune shifts induced by space charge effects cause beam loss which limits the beam intensity. To achieve further high beam intensity at the main ring of the Japan Proton Accelerator Research Comp…
View article: Real-time correction of betatron tune ripples on a slowly extracted beam
Real-time correction of betatron tune ripples on a slowly extracted beam Open
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.…
View article: A Control System of New Magnet Power Converter for J-PARC Main Ring Upgrade
A Control System of New Magnet Power Converter for J-PARC Main Ring Upgrade Open
Japan Proton Accelerator Research Complex (J-PARC) aims at a MW-class proton\naccelerator facility. One of the promising solutions for increasing the beam\npower of the Main Ring (MR) is converters of the main magnets with new ones for\nth…
View article: Search for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>K</mml:mi></mml:mrow><mml:mrow><mml:mi>L</mml:mi></mml:mrow></mml:msub><mml:mo stretchy="false">→</mml:mo><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup><mml:mi>ν</mml:mi><mml:mover accent="true"><mml:mrow><mml:mi>ν</mml:mi></mml:mrow><mml:mrow><mml:mo stretchy="false">¯</mml:mo></mml:mrow></mml:mover></mml:mrow></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>K</mml:mi><mml:mi>L</mml:mi></mml:msub><mml:mo stretchy="false">→</mml:mo><mml:msup><mml:mi>π</mml:mi><mml:mn>0</mml:mn></mml:msup><mml:msup><mml:mi>X</mml:mi><mml:mn>0</mml:mn></mml:msup></mml:math> Decays at the J-PARC KOTO Experiment
Search for and Decays at the J-PARC KOTO Experiment Open
A search for the rare decay K_{L}→π^{0}νν[over ¯] was performed. With the data collected in 2015, corresponding to 2.2×10^{19} protons on target, a single event sensitivity of (1.30±0.01_{stat}±0.14_{syst})×10^{-9} was achieved and no cand…
View article: Magnet Power Supply Calibration with a Portable Current Measuring Unit at the J-PARC Main Ring
Magnet Power Supply Calibration with a Portable Current Measuring Unit at the J-PARC Main Ring Open
In the J-PARC MR, 96 bending magnets (BMs) are used in total. They are divided into 6 groups of 16 BMs. The 16 BMs in each group are connected in series and driven by a single power supply. Since all 96 BMs are symmetrically located in the…
View article: A new search for the KL→π0νν¯ and KL→π0X0 decays
A new search for the KL→π0νν¯ and KL→π0X0 decays Open
We searched for the $CP$-violating rare decay of neutral kaon, $K_{L} \\to\n\\pi^0 \\nu \\overline{\\nu}$, in data from the first 100 hours of physics running\nin 2013 of the J-PARC KOTO experiment. One candidate event was observed while\n…
View article: Power Supplies for Main Magnet of J-PARC Main Ring
Power Supplies for Main Magnet of J-PARC Main Ring Open
A large magnetic field ripple of the order of 10⁻² were observed at the first beam commissioning of J-PARC main ring in 2008, To eliminate the ripple, we had improved the magnet power supplies by reconstructing a trap-filter of 600 Hz and …
View article: Long-lived neutral-kaon flux measurement for the KOTO experiment
Long-lived neutral-kaon flux measurement for the KOTO experiment Open
The KOTO ($K^0$ at Tokai) experiment aims to observe the CP-violating rare decay $K_L \\rightarrow \\pi ^0 \\nu \\bar {\\nu }$ by using a long-lived neutral-kaon beam produced by the 30 GeV proton beam at the Japan Proton Accelerator Resea…
View article: Development of J-PARC MR Main Magnets Power Supplies for High Repetition Rate Operation
Development of J-PARC MR Main Magnets Power Supplies for High Repetition Rate Operation Open
J-PARC aims at achieving a MW-class proton accelerator facility. One of the promising solutions for increasing the beam power is to fasten the repetition rate of MR from current rating of 2.5 sec to 1 sec. However, in this scheme, the incr…