US3311771A - Neutron generators - Google Patents
Neutron generators Download PDFInfo
- Publication number
- US3311771A US3311771A US290086A US29008663A US3311771A US 3311771 A US3311771 A US 3311771A US 290086 A US290086 A US 290086A US 29008663 A US29008663 A US 29008663A US 3311771 A US3311771 A US 3311771A
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- US
- United States
- Prior art keywords
- target
- ion source
- shield
- alpha
- ions
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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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
- H05H6/00—Targets for producing nuclear reactions
-
- 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
- H05H3/00—Production or acceleration of neutral particle beams, e.g. molecular or atomic beams
- H05H3/06—Generating neutron beams
Definitions
- This invention relates to neutron generators of the type in which an ion source generates ions which are accelerated across an acceleration gap by a potential difference applied across the gap, so as to strike a target material with high energy, the ion source and the acceleration gap being within a common sealed envelope at substantially the same pressure. It is necessary to have a short welldefined acceleration gap so as to keep the conditions well up the left hand side of the Paschen curve relating breakdown voltage to the product of the gas pressure and the acceleration distance.
- the gas pressure is normally within the range 1 to 1000x mm. pressure and the voltage across the acceleration gap is normally 10-200 kv.
- This invention provides a neutron generator of the type specified having an alpha particle counter inside the sealed envelope.
- the invention consists in a neutron generator of the type specified in which an electrostatic shield is positioned between the target and the ion source to provide one boundary of the acceleration gap and maintain a fieldfree zone within which the target is located, sa-id shield having an aperture for passage of ions from the ion source to the target, and a detection means for detecting alpha particles emitted by the target is mounted within the said field-free zone in direct view of the target.
- a sealed glass envelope 1 has an arm 2, containing a deuterium replenisher 3 as described in the first of the above references, and an arm 4 containing a Pirani pressure gauge 5.
- a tritium loaded target 6 is mounted within a metal cylindrical shield 7 by means of brackets 8 and 9.
- a mesh 10 provides an aperture for ions directed at the target.
- Cylinder 7 is supported on electrodes 11.
- a solid-state alpha counter 12 is mounted in a metal shield can 13 having an aluminium foil window 14, the window being opposite a port in cylinder 7 and being in full view of the target 6.
- the aluminium foil window (0.9 mgm/cm?) allows entry of the alpha particles but stops light and ions elastically scattered from the target.
- a cathode 15 has a heater 16 both supported by their stilt wire connections 17 and 18 respectively.
- a tubular anode 19 is supported on its connection 20.
- An extractor cathode 21 has a mesh 22 opposite the mesh 10, the distance between the two meshes constituting an acceler-ation gap.
- a coil not shown applies an axial magnetic field to the space between cathodes 1'5 and 21.
- the nu-mber of alpha particles counted is about fi of the total.
- the target and alpha counter are A held .at earth potential and a positive voltage of 60 kv. is applied to the extractor cathode, the anode voltage being about v. higher.
- the ion source current was 0.5 to 1 ma, providing an ion current of 5 to 10 ma. molecular ions.
- Alpha counter bias was 15 v. and amplified pulses can be fed to a multi-channel analyser and a timed scaler.
- the alpha counter used in one embodiment was made by diffusing phosphorus into 3000 ohm p-type silicon. Electrical connection to the phosphorus difiused. surface was made by using a silver paste as a glue for a fine wire.
- a neutron generator comprising a sealed envelope containing an electrostatic shield positioned between a target and an ion source to form one boundary of an accelerating gap and to provide a field-free zone on the side of the shield remote from the ion source, said target being located within said zone, said shield having an aperture for passage of ions from the ion source to the target, and means mounted in direct view of the target for detecting alpha particles emitted by the target, said detecting means being mounted within said field-free zone on the side of the shield remote from the ion source to prevent secondary electrons emitted from the target from being accelerated towards the detecting means.
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- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- High Energy & Nuclear Physics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Optics & Photonics (AREA)
- Particle Accelerators (AREA)
- Measurement Of Radiation (AREA)
Description
March 1967 J.ID. L. H. WOOD ETAL 3,311,771
NEUTRON GENERATORS Filed June 24, 1963 United States Patent 3,311,771 NEUTRON GENERATORS James David London Hedley Wood and Peter Donald Lomer, Letchworth, England, assignors to the United Kingdom Atomic Energy Authority, London, England Filed June 24, 1963, Ser. No. 290,086
Claims priority, application Great Britain, June 28, 1962,
3 Claims. (Cl. 31361) This invention relates to neutron generators of the type in which an ion source generates ions which are accelerated across an acceleration gap by a potential difference applied across the gap, so as to strike a target material with high energy, the ion source and the acceleration gap being within a common sealed envelope at substantially the same pressure. It is necessary to have a short welldefined acceleration gap so as to keep the conditions well up the left hand side of the Paschen curve relating breakdown voltage to the product of the gas pressure and the acceleration distance.
In such generators the gas pressure is normally within the range 1 to 1000x mm. pressure and the voltage across the acceleration gap is normally 10-200 kv.
Much information on neutron generators is available in published form and attention is directed to Review of Scientific Instruments, 31 (1960) 3 and to Nucleonics, vol. 18, No. 12, December 1960, pages 69-76 which give descriptions of some sealed-off neutron generators.
In the calibration of neutron generators employing the DT reaction, it is customary to count the 3.5 m.e.v. alpha particle from the reaction T +D a+n+ 17.6 m.e.v. Alpha particles are, however, easily ahsorbedby even thin solid materials and the counting of alpha particles through the sealed envelope of sealed-off neutron generators is impossible. A thin window for passage of alpha particles through the envelope would be so thin that it would be too fragile and could not stand normal handling.
This invention provides a neutron generator of the type specified having an alpha particle counter inside the sealed envelope.
The invention consists in a neutron generator of the type specified in which an electrostatic shield is positioned between the target and the ion source to provide one boundary of the acceleration gap and maintain a fieldfree zone within which the target is located, sa-id shield having an aperture for passage of ions from the ion source to the target, and a detection means for detecting alpha particles emitted by the target is mounted within the said field-free zone in direct view of the target.
In this way Paschen breakdown between the alpha counter and the ion source is prevented, and secondary electrons given off by the target canno-t attain full acceleration potential and impinge on the counter.
An embodiment of the invention is illustrated by way of example in the accompanying drawing which is a diagrammatic general assembly.
In the drawing a sealed glass envelope 1 has an arm 2, containing a deuterium replenisher 3 as described in the first of the above references, and an arm 4 containing a Pirani pressure gauge 5. A tritium loaded target 6 is mounted within a metal cylindrical shield 7 by means of brackets 8 and 9. A mesh 10 provides an aperture for ions directed at the target. Cylinder 7 is supported on electrodes 11. A solid-state alpha counter 12 is mounted in a metal shield can 13 having an aluminium foil window 14, the window being opposite a port in cylinder 7 and being in full view of the target 6.
The can reduces pick up from plasma oscillations in the ion source and from RR waves originating in power supplies. The aluminium foil window (0.9 mgm/cm?) allows entry of the alpha particles but stops light and ions elastically scattered from the target.
A cathode 15 has a heater 16 both supported by their stilt wire connections 17 and 18 respectively. A tubular anode 19 is supported on its connection 20. An extractor cathode 21 has a mesh 22 opposite the mesh 10, the distance between the two meshes constituting an acceler-ation gap.
A coil not shown, applies an axial magnetic field to the space between cathodes 1'5 and 21.
With the geometry shown, the nu-mber of alpha particles counted is about fi of the total.
To operate the tube, the target and alpha counter are A held .at earth potential and a positive voltage of 60 kv. is applied to the extractor cathode, the anode voltage being about v. higher. With gas pressure of 20 microns and an axial magnetic field of 200 gauss, the ion source current was 0.5 to 1 ma, providing an ion current of 5 to 10 ma. molecular ions.
Alpha counter bias was 15 v. and amplified pulses can be fed to a multi-channel analyser and a timed scaler.
The alpha counter used in one embodiment was made by diffusing phosphorus into 3000 ohm p-type silicon. Electrical connection to the phosphorus difiused. surface was made by using a silver paste as a glue for a fine wire.
We claim:
1. A neutron generator comprising a sealed envelope containing an electrostatic shield positioned between a target and an ion source to form one boundary of an accelerating gap and to provide a field-free zone on the side of the shield remote from the ion source, said target being located within said zone, said shield having an aperture for passage of ions from the ion source to the target, and means mounted in direct view of the target for detecting alpha particles emitted by the target, said detecting means being mounted within said field-free zone on the side of the shield remote from the ion source to prevent secondary electrons emitted from the target from being accelerated towards the detecting means.
2. A neutron generator as claimed in claim 1 wherein the detecting means is a solid-state alpha-counter located behind a window which allows the entry of alpha particles to the counter while preventing the entry of light thereto.
3. A neutron generator as claimed in claim 1 wherein the electrostatic shield is a tube, said aperture for passage of ions from the ion source being at one end of the tube and of smaller diameter than the tube, said target being mounted within said tube at an angle to the direction of the ion beam and said detecting means being mounted in a side-arm sealed to the envelope, a port being provided in the wall of the tube to allow alpha particles from the target to reach the detector.
References Cited by the Examiner OTHER REFERENCES Hawkins et al., Compact Pulsed Generator of Fast Neutrons, The Review of Scientific Instruments, vol. 31, No. 3, March 1960, pages 241-248. Scientific Library, No. Q 184 R5, copy in 313-61.
JAMES W. LAWRENCE, Primary Examiner. DAVID J. GALVIN, R. JUDD, Assistant Examiners.
Claims (1)
1. A NEUTRON GENERATOR COMPRISING A SEALED ENVELOPE CONTAINING AN ELECTROSTATIC SHIELD POSITIONED BETWEEN A TARGET AND AN ION SOURCE TO FORM ONE BOUNDARY OF AN ACCELERATING GAP AND TO PROVIDE A FIELD-FREE ZONE ON THE SIDE OF THE SHIELD REMOTE FROM THE ION SOURCE, SAID TARGET BEING LOCATED WITHIN SAID ZONE, SAID SHIELD HAVING AN APERTURE FOR PASSAGE OF IONS FROM THE ION SORUCE TO THE TARGET, AND MEANS MOUNTED IN DIRECT VIEW OF THE TARGET FOR DETECTING ALPHA PARTICLES EMITTED BY THE TARGET, SAID DE-
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB24879/62A GB978521A (en) | 1962-06-28 | 1962-06-28 | Improvements to neutron generators |
Publications (1)
Publication Number | Publication Date |
---|---|
US3311771A true US3311771A (en) | 1967-03-28 |
Family
ID=10218702
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US290086A Expired - Lifetime US3311771A (en) | 1962-06-28 | 1963-06-24 | Neutron generators |
Country Status (4)
Country | Link |
---|---|
US (1) | US3311771A (en) |
FR (1) | FR1362827A (en) |
GB (1) | GB978521A (en) |
NL (1) | NL294529A (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3581093A (en) * | 1968-04-23 | 1971-05-25 | Kaman Sciences Corp | Dc operated positive ion accelerator and neutron generator having an externally available ground potential target |
US3784824A (en) * | 1970-01-23 | 1974-01-08 | Philips Corp | Tritium target with compensated sputtering |
WO2008100269A3 (en) * | 2006-06-09 | 2008-11-13 | Univ California | Compact neutron source and moderator |
CN106098507A (en) * | 2016-06-30 | 2016-11-09 | 西安冠能中子探测技术有限公司 | A kind of setl-target neutron tube fills tritium platform and fills tritium method |
CN107567174A (en) * | 2017-08-28 | 2018-01-09 | 西安工业大学 | A kind of neutron tube |
EP3832666A4 (en) * | 2018-08-02 | 2021-10-13 | Riken | Target structure and target device |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2958780A (en) * | 1956-10-29 | 1960-11-01 | Schlumberger Well Surv Corp | Methods and apparatus for investigating earth formations |
US3043955A (en) * | 1960-01-25 | 1962-07-10 | Hughes Aircraft Co | Discriminating radiation detector |
US3110806A (en) * | 1959-05-29 | 1963-11-12 | Hughes Aircraft Co | Solid state radiation detector with wide depletion region |
US3158743A (en) * | 1961-02-23 | 1964-11-24 | Schlumberger Well Surv Corp | Semiconductor junction device for monitoring radioactivity in a well logging sonde |
US3205357A (en) * | 1962-04-18 | 1965-09-07 | William F Lindsay | Solid state radiation detector |
-
1962
- 1962-06-28 GB GB24879/62A patent/GB978521A/en not_active Expired
-
1963
- 1963-06-24 US US290086A patent/US3311771A/en not_active Expired - Lifetime
- 1963-06-25 NL NL294529D patent/NL294529A/xx unknown
- 1963-06-26 FR FR939479A patent/FR1362827A/en not_active Expired
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2958780A (en) * | 1956-10-29 | 1960-11-01 | Schlumberger Well Surv Corp | Methods and apparatus for investigating earth formations |
US3110806A (en) * | 1959-05-29 | 1963-11-12 | Hughes Aircraft Co | Solid state radiation detector with wide depletion region |
US3043955A (en) * | 1960-01-25 | 1962-07-10 | Hughes Aircraft Co | Discriminating radiation detector |
US3158743A (en) * | 1961-02-23 | 1964-11-24 | Schlumberger Well Surv Corp | Semiconductor junction device for monitoring radioactivity in a well logging sonde |
US3205357A (en) * | 1962-04-18 | 1965-09-07 | William F Lindsay | Solid state radiation detector |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3581093A (en) * | 1968-04-23 | 1971-05-25 | Kaman Sciences Corp | Dc operated positive ion accelerator and neutron generator having an externally available ground potential target |
US3784824A (en) * | 1970-01-23 | 1974-01-08 | Philips Corp | Tritium target with compensated sputtering |
WO2008100269A3 (en) * | 2006-06-09 | 2008-11-13 | Univ California | Compact neutron source and moderator |
US20100061500A1 (en) * | 2006-06-09 | 2010-03-11 | The Regents Of The University Of California | Compact neutron source and moderator |
CN106098507A (en) * | 2016-06-30 | 2016-11-09 | 西安冠能中子探测技术有限公司 | A kind of setl-target neutron tube fills tritium platform and fills tritium method |
CN106098507B (en) * | 2016-06-30 | 2018-01-12 | 西安冠能中子探测技术有限公司 | A kind of setl-target neutron tube fills tritium platform and its fills tritium method |
CN107567174A (en) * | 2017-08-28 | 2018-01-09 | 西安工业大学 | A kind of neutron tube |
EP3832666A4 (en) * | 2018-08-02 | 2021-10-13 | Riken | Target structure and target device |
US11985755B2 (en) | 2018-08-02 | 2024-05-14 | Riken | Target structure and target device |
Also Published As
Publication number | Publication date |
---|---|
GB978521A (en) | 1964-12-23 |
FR1362827A (en) | 1964-06-05 |
NL294529A (en) | 1965-04-12 |
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