U.S. patent application number 10/191380 was filed with the patent office on 2003-01-23 for multiple target, multiple energy radioisotope production.
This patent application is currently assigned to Advanced Molecular Imaging Systems, Inc.. Invention is credited to Grande, Pierre, McDaniel, Floyd Del, Morgan, Ira Lon, Watson, Jerry M..
Application Number | 20030015666 10/191380 |
Document ID | / |
Family ID | 22315598 |
Filed Date | 2003-01-23 |
United States Patent
Application |
20030015666 |
Kind Code |
A1 |
Morgan, Ira Lon ; et
al. |
January 23, 2003 |
Multiple target, multiple energy radioisotope production
Abstract
A multiple target array for receiving particles from a particle
beam generator includes a particle beam transport path having a
transport inlet and a transport outlet, the inlet receiving a
particle beam from the particle beam generator. A kicker magnet is
positioned along the particle beam transport path. The kicker
magnet has an ON state and an OFF state and a kicker magnet inlet
and a kicker magnet outlet. The array further includes a plurality
of target paths, each of said target paths having a target inlet
and terminating in a target. One of the target inlets is connected
to the transport path adjacent to the kicker magnet outlet, and the
particle beam in the transport path entering the kicker magnet
inlet passes along the transport path through the kicker magnet
outlet when the kicker magnet is in the OFF state, and the beam is
directed to the target inlet when the kicker magnet is in the ON
state.
Inventors: |
Morgan, Ira Lon; (Denton,
TX) ; McDaniel, Floyd Del; (Denton, TX) ;
Grande, Pierre; (Santa Fe, NM) ; Watson, Jerry
M.; (Midlothian, TX) |
Correspondence
Address: |
Attention: Barry S. Newberger
Winstead Sechrest & Minick P.C
5400 Renaissance Tower
1201 Elm Street
Dallas
TX
75270-2199
US
|
Assignee: |
Advanced Molecular Imaging Systems,
Inc.
|
Family ID: |
22315598 |
Appl. No.: |
10/191380 |
Filed: |
July 8, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10191380 |
Jul 8, 2002 |
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09432259 |
Nov 2, 1999 |
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6444990 |
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60107238 |
Nov 5, 1998 |
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Current U.S.
Class: |
250/398 |
Current CPC
Class: |
G21G 1/10 20130101; H05H
7/10 20130101 |
Class at
Publication: |
250/398 |
International
Class: |
H01J 003/26 |
Claims
What is claimed is:
1. A multiple target array for receiving particles from a particle
beam generator comprising: a particle beam transport path having a
transport inlet and a transport outlet, said inlet receiving a
particle beam from the particle beam generator; a kicker magnet
positioned along said particle beam transport path, said kicker
magnet having an ON state and an OFF state and a kicker magnet
inlet and a kicker magnet outlet; a plurality of target paths, each
of said target paths having a target inlet and terminating in a
target; wherein one of said target inlets is connected to said
transport path adjacent to said kicker magnet outlet, and wherein
the particle beam in said transport path entering said kicker
magnet inlet passes along said transport path through said kicker
magnet outlet when said kicker magnet is in the OFF state, and said
beam is directed to said target inlet when said kicker magnet is in
said ON state.
2. The multiple target array of claim 1 further comprising a
plurality of kicker magnets disposed along said particle beam
transport path and wherein one of said plurality of target inlets
are connected to said transport path adjacent to one of said
plurality of kicker magnets outlets.
3. The multiple target array of claim 2 further comprising a
deflecting magnet disposed in each of said plurality of target
paths for deflecting the beam in said target path, thereby allowing
a bend in said target path.
4. The multiple target array of claim 1 further comprising a
plurality of particle beam accelerators.
5. The multiple target array of claim 4 wherein said plurality of
particle beam accelerators comprise linear accelerators positioned
in a sequential array.
6. The multiple target array of claim 1 further comprising a
plurality of focusing magnets in said transport path positioned
between the particle beam generator and said kicker magnet.
7. An apparatus for producing particle beams at multiple energy
levels comprising a plurality of linear accelerators, each of said
plurality of linear accelerators having an accelerator inlet and an
accelerator outlet wherein said plurality of linear accelerators
are positioned with an accelerator outlet of one linear accelerator
connected to an accelerator outlet of a next linear accelerator to
create a sequential array.
8. The apparatus of claim 7 further comprising: a particle beam
transport path having a transport inlet and a transport outlet,
said inlet connected to one of said accelerator outlets at a
termination of said sequential array; a plurality of target paths,
each of said target paths having a target inlet and termination in
a target; a plurality of kicker magnets positioned adjacent to said
particle beam transport path, each of said plurality of kicker
magnets having an ON state and an OFF state and a kicker magnet
inlet and a kicker magnet outlet; wherein each of said plurality of
target inlets is connected to said transport path adjacent to a
corresponding kicker magnet outlet and said transport outlet is
connected to one of said target inlets, and wherein each of said
kicker magnet inlets receives said beams, passes said beams through
said kicker magnet outlet along said transport path when said
kicker magnet is in the OFF state, and redirects said beam to said
target inlet when said kicker magnet is in said ON state.
9. The multiple target array of claim 8 further comprising a
plurality of focusing magnets in said transport path positioned
between said sequential array of said particle beam accelerators
and plurality of kicker magnets.
10. The multiple target array of claim 9 further comprising a
deflecting magnet disposed in each of said plurality of target
paths for deflecting the beam in said target path, thereby allowing
a bend in said target path.
11. A particle beam transport system comprising: a sequential array
of particle beam accelerators having an array beam outlet; a
particle beam transport path having a transport inlet and a
transport outlet, said inlet connected to said array beam outlet
for receiving a particle beam; a plurality of focusing magnets on
said particle beam transport path; a plurality of target paths,
each having a target inlet and terminating in a target; a plurality
of kicker magnets disposed along said particle beam transport path,
each of said plurality of kicker magnets having an ON state and an
OFF state and a kicker magnet inlet and a kicker magnet outlet;
wherein one of said target inlets is connected to said transport
path adjacent to a one of said kicker magnet outlets, said
transport outlet is connected to one of said target inlets, said
focusing magnets focus said beam for said plurality of kicker
magnet inlets, and each of said plurality of kicker magnet inlets
receives said beam, passes said beam through said kicker magnet
outlet along said transport path when said kicker magnet is in the
OFF state, and directs said beam to said tartet inlet when said
kicker magnet is in said ON state.
12. The system of claim 11 further comprising a plurality of pulsed
power supplies, wherein one of said kicker magnets and one of said
focusing magnets is powered by one of said pulsed power
supplies.
13. The system of claim 12 further comprising a controller for
controlling said plurality of pulsed power supplies.
14. The system of claim 13 further wherein said each of said
plurality of kicker magnets comprises pulsed dipole magnets.
15. The system of claim 14 wherein said each of said plurality of
focusing magnets comprises quadropole magnets.
16. The system of claim 15 further comprising a deflecting magnet
disposed in each of said plurality of target paths to deflect said
beam in said target path, thereby allowing a bend in said target
path.
17. The system of claim 16 wherein each of said plurality of
deflecting magnets comprises dipole magnets.
18. A method of producing multiple radioisotopes from alternative
pulses of a particle beam comprising: producing a pulsed particle
beam of discrete pulses at a preselected energy level for each
pulse; directing each of the pulses along a defined transport path
having alternative target branches, wherein each of the alternative
target branches terminates in a target where radioisotopes are
produced; and directing a selection of the pulses on the transport
path into an alternative target branch using pulsed kicker magnets
disposed on the transport path.
19. The method of claim 18 further comprising deflecting the pulses
traversing the target branches to follow bends in the target
branches.
20. The method of claim 19 further comprising focusing each pulse
as it traverses the transport path.
Description
RELATED APPLICANTION
[0001] This application relies on provisional application Serial
No. 60/107,238, filed Nov. 5, 1998, and entitled "Multiple Target,
Multiple Energy Radioisotope Production".
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a multiple target station
for multiple energy particle beam bombardment. The apparatus and
method have particular utility in connection with radioisotope
production.
[0004] 2. Description of Related Information
[0005] The use of cyclotrons and linear accelerators for
radioisotope production is known in the art. To produce a
radioisotope, the accelerated particle beam produced by a cyclotron
or linear accelerator is used to bombard a target.
[0006] For efficiency of production, it is desirable to
simultaneously bombard multiple targets at multiple energies. To
bombard multiple targets, geometrical splitting techniques are used
on the accelerated particle beam. One such technique known in the
art employs stripping foils, which may be configured to create
electrostatic extraction channels to split the beam. However, the
use of stripping foils creates limitations: only two, or perhaps
three, targets can be simultaneously bombarded. An even greater
drawback is that each individual target station is limited to a
fixed, predetermined energy and a set fraction of the incident
beam.
SUMMARY OF THE INVENTION
[0007] The present invention does not limit the number of targets
that may be simultaneously bombarded. Additionally, each target may
be used for the entire range of available energies. A further
advantage of the present invention is that the fraction of the
incident beam and the energy bombarding a single target can be
readily adjusted.
[0008] The present invention employs a series of magnets placed
along the path of the particle beam to control the beam. The
magnets allow the beam to be focused, permitting the use of
multiple energy levels. The magnets also allow the pulses of a
pulsed particle beam to be directed towards individual targets on a
pulse-by-pulse basis. Linear accelerators allow for particle beam
pulses, or bursts, of several predetermined energy levels to be
generated in a particle beam path.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] For a more complete understanding of the present invention
and for further advantages thereof, reference is now made to the
following Description of the Preferred Embodiments taken in
conjunction with the accompanying Drawings in which:
[0010] FIG. 1 depicts a particle beam transport system terminating
in multiple target areas;
[0011] FIG. 2 depicts a sequential array of linear
accelerators;
[0012] FIG. 3 depicts a multiple target array; and
[0013] FIG. 4 is an expanded view of a kicker magnet, and the
transport path and target path at the kicker outlet.
DESCRIPTION OF THE PRESENT EMBODIMENT
[0014] Referring now to FIG. 1, an embodiment of a particle beam
transport system terminating in multiple target areas for a
multiple energy, multiple target linear accelerator system is
therein depicted, and is generally referred to by the numeral 10. A
sequential array of particle beam accelerators 12 provides a
particle beam. Connected to the sequential array 12 is a particle
beam transport tube or path 14. The transport path 14 is defined by
a sealed, enclosed tube. The purpose of the sealed tubular path is
to allow the particle beam to travel in a vacuum along a
predetermined route. A series of target paths 16 branch from the
transport path 14. Similar to the transport paths 14, the target
paths 16 are also sealed tubular enclosures. The target paths
terminate at targets 18. An additional target 18 is placed at the
termination of the transport path 14.
[0015] Turning now to FIG. 2, a sequential array 12 of linear
accelerator tanks 20 is depicted. In the present embodiment of the
invention, four drift tube linear accelerator tanks 20 arc placed
sequentially, or end-to-end, to create the sequential array 12. In
this arrangement, the accelerator outlet 22 of one accelerator tank
20 is connected to the accelerator inlet 24 of the next accelerator
tank 20 in a series, starting at an intial accelerator tank 20 and
terminating at a terminal accelerator tank 20. The drift tubes in a
linear accelerator tank 20 are pulsed to create a pulsed particle
beam consisting of a series of particle bursts, or pulses. In the
preferred embodiment, the pulses are output at a repetition rate of
360 Hz, which translates to a beam pulse every 2.8 milliseconds.
The use of multiple linear accelerator tanks 20 allows for particle
beams of a variety of energy levels to be generated. In the present
embodiment of the invention, the first two linear accelerator tanks
20 are powered to generate a 33 meV particle beam. The third
accelerator tank 20 may be used in conjunction with the first two
tanks to produce a 51 meV particle beam, and all four accelerator
tanks 20 may be used to produce a 70 meV beam. It will be apparent
to those skilled in the art that different combinations of
accelerators can be used to produce different or additional energy
levels. The drift tubes in the accelerator tanks 20 can be pulsed
on and off to vary the particle beam energy level from pulse to
pulse.
[0016] FIG. 3 depicts a multiple target array. The target array
comprises the transport path 14 from the outlet 24 of the last
accelerator tank 20, the target paths 16 deviating from the
transport path 14 and the targets 18. The transport path 14, which
is a sealed, enclosed tube 14, has a transport inlet 26 for
receiving a particle beam from the particle accelerator tanks 20
(FIG. 3). The transport inlet 26 is connected to the accelerator
outlet 24 at the termination of the sequential array 12. The
transport path 14 terminates at a transport outlet 28.
[0017] A series of focusing magnets 30 are situated downstream of
the transport inlet 26 along the transport path 14. After a pulsed
particle beam produced by the sequential array 12 enters the
transport path 14, the beam passes through the series of focusing
magnets 30.
[0018] In the present embodiment, a series of four pulsed
quadropole magnets are used as focusing magnets 30. The magnets
have a central orifice through which the beam flows. For purposes
of this invention, when a beam enters, travels or traverses,
through a magnet, the point of entry into which the beam path
enters the central orifice of the magnet is referred to as an
inlet, and the point at which the beam path exits the central
orifice is referred to as an outlet. In the present embodiment, all
of the magnets are external to the transport path 14, such that the
transport tube 14 passes through the central orifice of the magnet.
The inlet and outlet nomenclature is also used when the beam enters
or exits a tube or path, such as the transport path 14 or a target
path 16, and the accelerator tanks 20.
[0019] The focusing magnets 30 are used to adjust, or focus, the
particle beam. The pulsing of the focusing magnets 30 acts upon
particle beams of different energy levels traversing the set
transport path 14. A different magnetic field is required to
properly focus the particle beam for each different energy level of
pulse. The magnetic field generated by a focusing magnet 30 is
varied by varying the current to the focusing magnet 30 from pulse
to pulse. Each quadropole magnet 30 is powered by an individual
pulsed power supply, which allows the current to be varied from
pulse to pulse.
[0020] After the particle beam pulse is focused by the focusing
magnets 30, the particles in the beam pulse travel further along
the transport path 14. A series of kicker magnets 32 are disposed
along the transport path 14 between the focusing magnets 30 and the
transport outlet 28. Referring to FIG. 4, each kicker magnet 32 has
a kicker inlet 34 through which the beam enters and a kicker outlet
36 through which the beam exits. In the present embodiment, pulsed
dipole magnets located at regular intervals along the path serve as
kicker magnets 32. The kicker magnets 32 can be pulsed by an
electrical current, placing the kicker magnet 32 in an "on" state.
When the kicker magnet 32 is on, magnet 32 will act upon the beam
pulse traveling through the kicker magnet 32 by causing the pulse
to deviate from the transport path 14. When the pulsed dipole
magnet 32 is not pulsed by a current, the kicker magnet 32 is in
its "off" state, and a beam traveling through the magnet is
unaffected.
[0021] Target paths 16 branch, or deviate, from the transport path
14 and terminate in target stations 18. A beam enters the target
path 16 through its target inlet 38. The target paths 16 branch off
the transport path 14; the target inlets 38 are disposed adjacent
to the kicker outlet 36 of each kicker magnet 32. The transport
path 14 actually extends through the central orifice of the kicker
magnet 32. At the kicker outlet 36, the transport path 14
continues, but a separate target path 16 deviates from the
transport path 14 just after the transport path exits the kicker
outlet 14.
[0022] In the preferred embodiment, the target paths 16 deviate
from the transport path 14 at 14.degree. angles. This angle was
selected by the ability of a kicker magnet 32 to respond to a beam
pulse of maximum system strength, which has been given as 70 meV in
the present embodiment. It will be apparent to those skilled in the
art that a different angle could be used for kicker magnets of
different strengths or for different maximum beam energy levels.
Because the incident angle of the target path 14 is fixed in the
system of the present invention, the strength of the magnetic field
produced by the kicker magnet 32 must be adjusted for the energy
level of the beam pulse, so that the beam pulse enters the target
path 16. The variation in the strength of the magnetic field
produced by the kicker magnet 32 is achieved by varying the current
to the kicker magnet 32.
[0023] Returning to FIG. 3, it should be noted that for physical
layout purposes, it is desirable to minimize the length of the
transport path 14 and the target paths 16 and the area between the
target stations 18. The paths may be shortened, and the target
stations 18 may be placed closer to one another, by bending the
target paths 16. The beam pulse is steered along the bent target
path 16 through the use of a deflecting magnet 40. In the present
invention, a dipole bending magnet is used as a deflecting magnet
40. The target path 16 is bent at a 31.degree. angle, so the
deflecting magnet 40 is energized to deflect each pulse traversing
the target path 16 at that angle to maintain a beam pulse along the
target path 16. It will be apparent to one skilled in the art that
different angles, different or additional deflecting magnets, or
variations in placement of the target stations 18 relative to the
transport path 14 could be used for different physical layouts.
[0024] In the present embodiment, a total of five kicker magnets 32
are employed. Each of the five kicker magnets 32 can deviate a
particle beam into a target path 16 terminating in a target 18. The
target inlet 38 of an additional target path 16 is connected to the
terminal outlet 28. In the present embodiment, a deflecting magnet
40 is not present in the target path 16 connected to the terminal
outlet 28, in order to minimize the length of the particular target
path. The target 18 of this particular target path 16 may also be
used as a dump station for unwanted pulses. Therefore, the
described embodiment has a total of six targets 18. However, the
number of kicker magnets 32 can be varied to vary the number of
targets 18.
[0025] To allow the electrical current input to each kicker magnet
32 to be readily adjusted, each kicker magnet 32 is powered by an
individual pulsed power supply. Individual power supplies allow the
current to each kicker magnet 32 to be individually selected, so
that each kicker magnet 32 can be turned on and off individually.
The focusing magnets 30 are also powered by individual pulsed power
supplies which allows the magnetic field of each individual
focusing magnet 32 to be set independently. Therefore, the spacing
between the focusing magnets 30 does not limit the system to a
particular beam wavelength.
[0026] In the present invention, a computerized control system
controls the power supply for each focusing magnet 30 and for each
kicker magnet 32. The power supplies ultimately control the state
and the strength of the magnetic field output of each kicker magnet
32 or focusing magnet 30. In the case of the focusing magnets 30,
the control system adjusts the current, which powers the magnets to
an appropriate level for the power of each particle beam pulse. In
the case of the kicker magnets 32, the control system controls the
state of each kicker magnet 32, determining whether a beam pulse is
sent to the target 18 associated with the kicker magnet 32 or
further down the transport path, as well as the strength of the
kicker magnet 32 field. For example, the control system controls
the pulsed power supply for the first pulsed kicker magnet 32 to
output a selected current pulse, such that the pulsed magnet
reaches a proper magnetic field level to divert the desired beam
pulse by 14.degree. before a desired beam pulse enters the kicker
magnet 32 which causes the desired beam pulse to deflect to the
first target station 18. The current may then be controlled so that
the magnetic field level in the pulsed kicker magnet 32 will return
to zero (placing the kicker magnet 32 in its "off" state) before
the next beam pulse arrives. For the next pulse, when the power
supply does not output a pulsed current, the beam pulse will not be
deflected and will travel to the next kicker magnet 32. If the
second kicker magnet 32 receives an appropriate current pulse from
its power supply, the beam pulse will be deflected to the second
target station 18. If no current pulse is sent from the power
supply of the second kicker magnet 32 to the magnet, the beam will
continue to the third kicker magnet 32.
[0027] The controller repeats the above selection process at each
kicker magnet 32, thus allocating the beam pulses amongst the
multiple targets 18. If no kicker magnets 32 are pulsed, the beam
pulse is directed to a beam dump or target 18 beyond the transport
outlet 28. Different energy beams are directed to the desired
target 18 by ensuring that the proper magnetic field level is
produced in the kicker magnets 32.
[0028] Additions to the present invention can be employed to ensure
an efficient system. For example, FODO (focusing-defocusing)
quadropole magnets may be placed along the transport path 14 to
maintain the beam focus as it traverses the transport path 14.
Sensors placed along the transport path 14 can relay data to a
computerized control system. Focusing magnets in the target path 16
immediately prior to the targets 18 can ensure the precision of the
beam prior to its bombardment into the target 18. These magnets are
set to bend and focus the desired output beam pulse.
[0029] While a preferred embodiment of the a particle beam
transport system terminating in multiple target areas has been
described in detail, it should be apparent that modifications and
variations thereto are possible, all of which fall within the true
spirit and scope of the invention. For example, the present
invention may be adapted for use with any suitable particle beam
accelerator; a different number of accelerators could be used for a
different number of energy levels; and the multiple energy levels
could be achieved by funneling the output of multiple particle beam
accelerators with deflecting magnets rather than using sequential
placement. Different types of beam path energizers may be
substituted for the magnets. The controller may consist of a
microprocessor or other computerized devices. Additionally,
different configurations of magnets can be used to allow for
additional target areas.
[0030] Whereas the present invention has been described with
respect to specific embodiments thereof, it will be understood that
various changes and modifications will be suggested to one skilled
in the art and it is intended to encompass such changes and
modifications as fall within the scope of the appended claims.
* * * * *