US3921019A - Self-shielding type cyclotron - Google Patents

Self-shielding type cyclotron Download PDF

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Publication number
US3921019A
US3921019A US417929A US41792973A US3921019A US 3921019 A US3921019 A US 3921019A US 417929 A US417929 A US 417929A US 41792973 A US41792973 A US 41792973A US 3921019 A US3921019 A US 3921019A
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Prior art keywords
yoke
cyclotron
pole
dees
radiation
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Expired - Lifetime
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US417929A
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English (en)
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Takashi Karasawa
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RIKEN
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RIKEN
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Priority claimed from JP12353872A external-priority patent/JPS5032400B2/ja
Priority claimed from JP12362973A external-priority patent/JPS5123675B2/ja
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H13/00—Magnetic resonance accelerators; Cyclotrons
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H11/00—Magnetic induction accelerators, e.g. betatrons

Definitions

  • PRIOR ART FIG.2 PRIOR ART US. Patent Nov. 181 1975 Sheet20f3 3,921,019
  • This invention relates to an improvement in; or relating to a cyclotron, and more-particularly to a-.-selfshielding type cyclotron which makes it unnecessaryto enclose the cyclotron by an extra shielding structure to protectpersonnel or equipment from radiation injury or damage.
  • I t I Referring to FIGS. 1 and 2, there is shown a-conventional cyclotron in which a vacuum casing ,3 contains two accelerating electrodestcalled dees) 2, and is disposed between thepoles l of a magnetstructure.
  • the opening defined by the oppositeyokes9 of the magnet structure there are together disposed a high-frequency,powerinlet4 to the dees, an exhaust 6 to a vacuum purnp and anoutlet 8 for extracting ions.
  • the ions are accelerated and deflected by a deflector 7..
  • theopening defined. by.t he magnet'yokes 9, will leakradiation whilelthecyclotron is running, and therefore it is necessary that an extra shield structure to .surround the cyclotron be providedto protect personnel or equipment from radiation injury or damage. Inthis connectiori the' floor space required for installation of the cyclotron is as large as the floor space of the cyclotron per se plus that ofgthe shielding structure.
  • cyclotron of this type has a resonato'r an exhaust, an ion outlet and other accessaries disposed. in the" epening of the magnet structure, and therefore it also necessitates a radiation-shielding structure.
  • the object of this invention is to provide a selfshield ing type cyclotron which is compact and less expensive
  • FIG. 1 is a plan view of a tiallybroken
  • FIG. ,2 is a side view of the conventional cyaieaenas shown in FIG. l; e Y f FIG. 3 is a vertical section of a cyclotron accordin gto this invention; f a v I i I FIG. 4 is a cross section of the cyclotron, taken along the line o-.o in FIG.' 3;and
  • FIGS. Sand 6 are similar to FIGS. "3 and'4, but showing another embodiment of this invention.
  • a cyclotron according to this invention comprises a pair of annular bodies A, A, integrally assembled in the over laying relation.
  • An annular body has a center leg portion 11 (hereinafter referred to as pole) and a peripheral leg (hereinafter referred to as yoke), thus taking a form of the letter E in vertical section.
  • 13 is an electromagnet coil (called Bitter type electromagnet); 15 dees positioned in the first space 14 defined by the opposite poles 11; 17 a target box mounted in the second space 16 defined by the opposite magnet coils 13; 19 coaxial elementsof the resonator disposed in the central apertures 18 of the poles and connected to the dees; and 20 a wall for keeping the first space 14 vacuum-tight.
  • 21 is a short-circuit plate of the coaxial elements; 22 a beam deflector; 23 is an ion source 24 a vacuum-tight gasket; 25 linear shafts which allow a hyvbody A; and finally 26 an exhaust duct to the. vacuum pump- (not shown).
  • I l electromagnet coil
  • a cyclotron is consisted of a pair of annular counterparts integrally connected in a vacuum-tight-fashion. Within this vacuum-tight assembly there are disposed a vacuum box, a target box and other accessories. Thanks to this unique structure, and if the wall of the yoke 10 has a thickness enough to prevent radiation from passing through the yoke. little or no radiation will appear outside of the cyclotron.
  • the shielding capability .of a cyclotron according to this invention will be discussed, taking the operating condition of 4 MeV, 10 uA deutron as an example. 'y-ray and neutron will be generated when deutron is accelerated in the cyclotron. However, if the shielding against neutron is satisfied, then the shielding against y-ray will suffice. In this connection the shielding capability; against neutron is handled in the following. In the event of bombardment against a Be target by the deutron as specified above, a large number of neutrons will be produced, and. for the operating condition above mentioned the number of neutrons thus gener .ated is:. 1
  • the amount of radiation is 4 X l0 /cm sec.
  • the dose of neutrons (in terms of rem") depends on the energy of neutron, l-mr is equal to about IO/cm for thermal neutrons, and is equal to about I0"/cm for 100 'KeV fast neutrons.
  • thermal neutron is percent of the total number of neutrons, and KeV fast neutron is 20 percent. Therefore the dose rate of thermal and fast neutrons is 1.1 mr/sec.
  • targets other than the Be target such as CO N or H O target
  • the rate of generation of neutrons is approximately one tenth of that in case of the Be target, i.e., about 0.1 mr/sec.
  • the cyclotron is running for 30 hours per week.
  • the neutrons will be about l X 10 mr/week, whereas in case of targets other than the Be target the neutrons will be about I X 10 mr/week.
  • the allowable dose at the boundary of the controlled area is 30 mr/week.
  • the yoke of the assembly is made of an iron as thick as 30 cm. Most neutrons-take an oblique path in passing through the yoke wall, and therefore effective thickness of the yoke wall is as large as about 45 cm. As is well known, an iron sheet as thick as 15 cm will reduce the neutron flux 10 times. Therefore. a 45 cm-thick iron sheet will reduce the neutron flux l.000 times.
  • the radiation dose at a l m-distance will be 100 mr/week, whereas in case of targets other than the Be target the radiation dose will be 10 mr/week.
  • the radiation dose is three times as large as the allowable value, and therefore the controlled area must extend and cover 2 meters around the cyclotron.
  • the cyclotron may be applied by a paraffin coating several centimeters thick.
  • the radiation dosev is one third of the allowable value, causing no radiation injury ordamage.
  • FIGS. and 6 there are shown another embodiment of this invention.
  • This cyclotron is structurally the same as the first embodiment of FIGS. 3 and 4 except for; the coaxial elements 19 of the resonator system extend through the yoke of the annular assembly to the dees l5, and the second space 16 is partially loaded with a shielding material 27 (such as paraffin or boron-and-paraffin mixture coated with a cadmium plate) around each coaxial unit.
  • a shielding material 27 such as paraffin or boron-and-paraffin mixture coated with a cadmium plate
  • This structure is advantageous to the integral connection between the dees l5 and the coaxial element 19, assuring a sufficient mechanical strength in the joint. Also, this arrangement permits the use of an integral type resonator in place of the split type-one, thus avoiding the unstable operation which would be caused by any misalignment of respective counterparts of the split type resonator when assembled.
  • the leak of the radiation from a target box can be prevented by putting a 30 cm-thick, cadmium-coated paraffin or paraffin-and-boron mixture layer on the coaxial element of the resonator in the second space.
  • These particular shielding materials as thick as cm will decrease neutron flux 10 times.
  • the coaxial element of the resonator is, for instance, 15 cm in diameter and cm in length.
  • the neutrons when passing through this cylindrical duct are supposed to decrease about 30 flO 4 times.
  • the neutron flux will decrease l,800 (1/60 X 1/30 1/1800). This figure proves the satisfactory self-shielding attained in a cyclotron according to this invention.
  • a cyclotron according to this invention is a closed structure, contrary to the conventional open-type cyclotron. Usually a 30 cm-thick yoke is adequate to prevent the leak of radiation. The thickness of the yoke increases with the energy of the cyclotron in designing.
  • the unique structure of this invention is advantageous particularly to a small-sized cyclotron having a target material other than Be (such as B, C, N, 0, Ne and other elements) for use in producing short-life radioisotopes for medical use, or in generating neutrons or charged particles for radiochemical analysis.
  • a target material other than Be such as B, C, N, 0, Ne and other elements
  • a cyclotron comprising: a pair of annular counterpart bodies overlying and integrally assembled with each other, each said annular counterpart body having, in section, a center leg comprising a pole and two side legs comprising a yoke in the form of the letter E, said yoke having a thickness adequate to prevent radiation from passing therethrough; electromagnet coils positioned around said pole and surrounded by said yoke; dees positioned in the first closed space defined by the opposite end surfaces of said pole; a target box positioned in the second space defined by the opposite surfaces of said electromagnet coils; a resonator comprising co-axial means inserted axially in central apertures of said poles and integrally connected to said dees; and gas-tight means for keeping vacuum at least in said first closedspace.
  • a cyclotron comprising: a pairof annular counterpart bodies overlying and integrally assembled with each other, each said annular counterpart body having, in section, a center leg comprising a pole and two side legs comprising a yoke in the form of the letter E", said yoke having a thickness adequate to prevent radiatiop from passing therethrough; electromagnet coils positioned around said pole and surrounded by said yoke; dees positioned in the first closed space defined by the opposite end surfaces of said pole; a target box positioned in the second space defined by the opposite surfaces of said electromagnet coils, a resonator comprising co-axial means extending transversely through said yokes and intergrally connected to said dees; radiation shield means positioned around said co-axial means in said second space; and gas-tight means for keeping vacuum at least in said first closed space.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)
US417929A 1972-12-04 1973-11-21 Self-shielding type cyclotron Expired - Lifetime US3921019A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP12353872A JPS5032400B2 (enrdf_load_stackoverflow) 1972-12-04 1972-12-04
JP12362973A JPS5123675B2 (enrdf_load_stackoverflow) 1973-11-02 1973-11-02

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5463291A (en) * 1993-12-23 1995-10-31 Carroll; Lewis Cyclotron and associated magnet coil and coil fabricating process
WO2005094142A3 (en) * 2004-03-29 2006-06-08 Nat Cardiovascular Ct Particle beam accelerator
US20070171015A1 (en) * 2006-01-19 2007-07-26 Massachusetts Institute Of Technology High-Field Superconducting Synchrocyclotron
US20070176699A1 (en) * 2005-03-29 2007-08-02 Japan As Represented By The President Of National Cardiovascular Center Particle beam accelerator
WO2008052616A1 (de) * 2006-10-28 2008-05-08 Smiths Heimann Gmbh Betatron mit herausnehmbaren beschleunigerblock
US20100282979A1 (en) * 2009-05-05 2010-11-11 Jonas Norling Isotope production system and cyclotron having a magnet yoke with a pump acceptance cavity
US20100282978A1 (en) * 2009-05-05 2010-11-11 Jonas Norling Isotope production system and cyclotron
US8374306B2 (en) 2009-06-26 2013-02-12 General Electric Company Isotope production system with separated shielding
US8575867B2 (en) 2008-12-05 2013-11-05 Cornell University Electric field-guided particle accelerator, method, and applications
CN106211536A (zh) * 2016-08-30 2016-12-07 中广核达胜加速器技术有限公司 一种中能半自屏蔽电子加速器

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2872574A (en) * 1956-04-12 1959-02-03 Edwin M Mcmillan Cloverleaf cyclotron
US3175131A (en) * 1961-02-08 1965-03-23 Richard J Burleigh Magnet construction for a variable energy cyclotron

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2872574A (en) * 1956-04-12 1959-02-03 Edwin M Mcmillan Cloverleaf cyclotron
US3175131A (en) * 1961-02-08 1965-03-23 Richard J Burleigh Magnet construction for a variable energy cyclotron

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5463291A (en) * 1993-12-23 1995-10-31 Carroll; Lewis Cyclotron and associated magnet coil and coil fabricating process
WO2005094142A3 (en) * 2004-03-29 2006-06-08 Nat Cardiovascular Ct Particle beam accelerator
US7888891B2 (en) 2004-03-29 2011-02-15 National Cerebral And Cardiovascular Center Particle beam accelerator
US20070176699A1 (en) * 2005-03-29 2007-08-02 Japan As Represented By The President Of National Cardiovascular Center Particle beam accelerator
US7696847B2 (en) * 2006-01-19 2010-04-13 Massachusetts Institute Of Technology High-field synchrocyclotron
US20070171015A1 (en) * 2006-01-19 2007-07-26 Massachusetts Institute Of Technology High-Field Superconducting Synchrocyclotron
US7541905B2 (en) * 2006-01-19 2009-06-02 Massachusetts Institute Of Technology High-field superconducting synchrocyclotron
US20090206967A1 (en) * 2006-01-19 2009-08-20 Massachusetts Institute Of Technology High-Field Synchrocyclotron
WO2008052616A1 (de) * 2006-10-28 2008-05-08 Smiths Heimann Gmbh Betatron mit herausnehmbaren beschleunigerblock
US20090267543A1 (en) * 2006-10-28 2009-10-29 Bermuth Joerg Betatron with a removable accelerator block
US7994740B2 (en) 2006-10-28 2011-08-09 Smiths Heimann Gmbh Betatron with a removable accelerator block
RU2479168C2 (ru) * 2006-10-28 2013-04-10 Смитс Хайманн Гмбх Бетатрон с извлекаемым блоком ускорителя
US8575867B2 (en) 2008-12-05 2013-11-05 Cornell University Electric field-guided particle accelerator, method, and applications
US20100282979A1 (en) * 2009-05-05 2010-11-11 Jonas Norling Isotope production system and cyclotron having a magnet yoke with a pump acceptance cavity
US20100282978A1 (en) * 2009-05-05 2010-11-11 Jonas Norling Isotope production system and cyclotron
US8106370B2 (en) 2009-05-05 2012-01-31 General Electric Company Isotope production system and cyclotron having a magnet yoke with a pump acceptance cavity
US8153997B2 (en) 2009-05-05 2012-04-10 General Electric Company Isotope production system and cyclotron
US8374306B2 (en) 2009-06-26 2013-02-12 General Electric Company Isotope production system with separated shielding
CN106211536A (zh) * 2016-08-30 2016-12-07 中广核达胜加速器技术有限公司 一种中能半自屏蔽电子加速器

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FR2209272A1 (enrdf_load_stackoverflow) 1974-06-28
FR2209272B1 (enrdf_load_stackoverflow) 1978-06-16

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