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| TUPSB52 | Measurement of the Argon Ion Current Accompanying at the Accelerating Source of Epithermal Neutrons | 334 |
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Funding: The reported study was funded by the Russian Foundation for Basic Research, project no. 19-32-90118. For the development of a promising method for the treatment of malignant tumors - boron neutron capture therapy - the accelerator-based epithermal neutron source has been proposed and created in the Budker Institute of Nuclear Physics. Argon ions formed during stripping of a beam of negative hydrogen ions to protons are accelerated and, in parallel with the proton beam, are transported along the high-energy beam line of the facility. Depending on the relative number of argon ions, their effect can vary from negligible to significant, requiring their suppression. In this work, the current of argon ions reaching the beam receiver in the horizontal high-energy beam line of the accelerator was measured. It was determined that the argon beam current accompanying the proton beam is 2000 times less than the proton beam current. This makes it possible not to apply the proposed methods of its suppression. |
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| DOI • | reference for this paper ※ doi:10.18429/JACoW-RuPAC2021-TUPSB52 | |
| About • | Received ※ 19 September 2021 — Revised ※ 27 September 2021 — Accepted ※ 29 September 2021 — Issued ※ 01 October 2021 | |
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| WEPSC30 | Measurement of the Phase Portrait of a 2 MeV Proton Beam Along Beam Transfer Line | 399 |
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Funding: The research was supported by Russian Science Foundation, grant No. 19-72-30005. For the development of boron neutron capture therapy - an accelerator source of epithermal neutrons has been proposed and created at the Budker Institute of Nuclear Physics (Novosibirsk, Russia). For future therapy it is necessary to ensure the transportation of a proton beam in a high-energy beam line at a distance of 10 meters. For this purpose, using a movable diaphragm with a diameter of 1 mm, mounted on a three-dimensional vacuum manipulator, and a wire scanner, the phase portrait of the proton beam was measured. The software for remote control of the movable diaphragm and data processing of the wire scanner was developed. An algorithm for processing a series of measurements was developed to reconstruct the image of the phase portrait of the beam and calculate the emittance. This work describes in detail the features of the measuring devices, control algorithms and data processing. An experiment was carried out to measure the phase portrait and emittance of a proton beam with an energy of 2 MeV and a current of up to 3 mA. A beam of neutral particles was also measured. The effect of a bending magnet on the focusing and emittance of the beam is studied. The invariant normalized emittances calculated from the measured phase portraits make it possible to assert that the beam can be transported over distances of about 10 meters without changes in the current geometry of the high-energy beam line. |
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| DOI • | reference for this paper ※ doi:10.18429/JACoW-RuPAC2021-WEPSC30 | |
| About • | Received ※ 10 September 2021 — Revised ※ 22 September 2021 — Accepted ※ 23 September 2021 — Issued ※ 11 October 2021 | |
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| WEPSC31 | 2D-Tomography of the Proton Beam in the Vacuum Insulated Tandem Accelerator | 402 |
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Funding: The research was supported by Russian Science Foundation, grant No. 19-72-30005. For the development of a promising method for the treatment of malignant tumors - boron neutron capture therapy - the accelerator-based epithermal neutron source has been proposed and created in the Budker Institute of Nuclear Physics. If the parameters of the proton beam change (energy and current of the beam, the parameters of the ion-optical system, the parameters of the ion source) - accordingly the conditions for the beam transportation change (its size, angular divergence, and position relative to the axis of the accelerator). For optimal conduction of the beam along the beam line, two-dimensional tomography of the beam can be used: using a cooled diaphragm with a diameter of several millimeters installed on a vacuum three-dimensional motion input and a Faraday cup, fast chord measurements are carried out, on the basis of which the beam profile is restored. The beam profile obtained by this way is somewhat different from the profile obtained by measuring the phase portrait of the beam using a wire scanner*. The advantage of this method is a relatively short time to restore the profile, depending on the diameter of the cooled diaphragm. * M. Bikchurina, at al. Measurement of the phase portrait and emittance of the proton beam and neutral atoms in the accelerator based epithermal neutrons source. These proceedings. |
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| DOI • | reference for this paper ※ doi:10.18429/JACoW-RuPAC2021-WEPSC31 | |
| About • | Received ※ 21 September 2021 — Revised ※ 29 September 2021 — Accepted ※ 09 October 2021 — Issued ※ 09 October 2021 | |
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| WEPSC32 | Proton Beam Size Diagnostics Used in the Vacuum Insulated Tandem Accelerator | 404 |
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Funding: The research was supported by Russian Science Foundation, grant No. 19-72-30005. For the development of a promising method for the treatment of malignant tumors - boron neutron capture therapy - the accelerator-based epithermal neutron source has been proposed and created in the Budker Institute of Nuclear Physics. After the acceleration phase, a proton beam with an energy of up to 2.3 MeV and a current of up to 10 mA is transported in a high-energy beam line. With a beam size of 1 cm2, its power density can reach tens of kW/cm2. Diagnostics of the size of such a powerful beam is a nontrivial task aimed at increasing the reliability of the accelerator. The paper presents such diagnostics as: 1) the use of the blister formation boundary during the implantation of protons into the metal; 2) the use of thermocouples inserted into the lithium target; 3) the use of the melting boundary of the lithium layer when it is irradiated with a beam; 4) the use of the activation of the lithium target by protons; 5) the use of video cameras; 6) the use of an infrared camera; 7) the use of the luminescence effect of lithium when it is irradiated with protons; 8) the use of collimators with a small diameter of 1-2 mm; 9) the use of the method of two-dimensional tomography*. * M. Bikchurina, et al 2D tomography of the proton beam in the vacuum-insulated tandem accelerator. These proceedings. |
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| DOI • | reference for this paper ※ doi:10.18429/JACoW-RuPAC2021-WEPSC32 | |
| About • | Received ※ 22 September 2021 — Revised ※ 29 September 2021 — Accepted ※ 09 October 2021 — Issued ※ 19 October 2021 | |
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| MOPSA47 | Verification of a Beam of Epithermal Neutrons for Boron-Neutron Capture Therapy | 199 |
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Funding: The research was supported by Russian Science Foundation, grant No. 19-72-30005. At Budker Institute of Nuclear Physics it was proposed and developed a source of epithermal neutrons based on a tandem accelerator with vacuum insulation and a lithium target for the development of boron neutron capture therapy, a promising method for treating malignant tumors. To measure the "boron" dose due to the boron-lithium reaction, a small-sized detector has been developed. It consists of two polystyrene scintillators, one of which is enriched with boron. Using the detector, the spatial distribution of boron dose and dose of gamma radiation in a 330x330x315 mm water phantom was measured and the results obtained were compared with the results of numerical simulation of the absorbed dose components in such a tissue-equivalent phantom. It is shown that the results obtained are in good agreement with the calculated ones. It was found that the use of a 72 mm Plexiglas moderator provides an acceptable quality of the neutron beam for in vitro and in vivo studies, namely: 1 mA 2.05 MeV proton beam on a lithium target provides a dose rate of 30 Gy-Eq/h in cells containing boron at a concentration of 40 ppm, and 6 Gy-Eq/h in cells without boron. The developed technique for on-line measurement of boron dose and dose of gamma radiation makes it possible to carry out a similar verification of a neutron beam prepared for clinical trials of BNCT after placing a neutron beam shaping assembly with a magnesium fluoride moderator in a bunker adjacent to the accelerator. |
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| DOI • | reference for this paper ※ doi:10.18429/JACoW-RuPAC2021-MOPSA47 | |
| About • | Received ※ 27 September 2021 — Revised ※ 28 September 2021 — Accepted ※ 09 October 2021 — Issued ※ 22 October 2021 | |
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| WEPSC28 | Optical Diagnostics of 1 MeV Proton Beam in Argon Stripping Target of a Tandem Accelerator | 393 |
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Funding: The research was supported by Russian Science Foundation, grant No. 19-72-30005. A neutron source for boron neutron capture therapy based on a vacuum-insulated tandem accelerator has been developed and operates at Budker Institute of Nuclear Physics. Conducting a ~10 mm proton beam with a power of up to 20 kW through a system of accelerating electrodes and 16 mm argon stripping tube is not an easy task. Any mistake made by operator or a malfunction of the equipment responsible for the correction of the beam position in the ion beam line can lead to permanent damage to the accelerator. To determine the position of the proton beam inside the argon stripping tube, optical diagnostics have been developed based on the Celestron Ultima 80-45 telescope and a cooled mirror located at an angle of 45 degrees to the beam axis in the straight-through channel of the bending magnet. The cooled mirror also performs the function of measuring the neutral current due to the electrical isolation of the mirror and the extraction of secondary electrons from its surface. The luminescence of a beam in the optical range, observed with the help of the developed diagnostics, made it possible for the first time to determine beam size and position inside the stripping tube with an accuracy of 1 mm. The light sensitivity of the applied optical elements is sufficient for using a shutter speed from 2 to 20 ms to obtain a color image of the beam in real time. This makes it possible to realize a fast interlock in case of a sudden displacement of the beam. |
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| DOI • | reference for this paper ※ doi:10.18429/JACoW-RuPAC2021-WEPSC28 | |
| About • | Received ※ 24 September 2021 — Revised ※ 26 September 2021 — Accepted ※ 27 September 2021 — Issued ※ 04 October 2021 | |
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