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Патент USA US3056033

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Sept. 25, 1962
Filed Nov. 18, 1960
?M é. W
if; tats
>Patented Sept. 25, 1962
Leona Marshall, Bellport, N.Y., assignor to the United
States of America as represented by the United States
Atomic Energy Commission
Filed Nov. 18, 1960, Ser- No. 79,877
6 Claims. ((11. 250—41.9)
consideration of the following speci?cation relating to the
accompanying drawing in which:
FIG. 1 is a diagrammatic illustration of the principles
involved in this invention; and
FIG. 2 is a simple magnetic lens system in which a
small degree of separation of particles is obtained.
It is known that beams of high energy particles may
be piped over long distances by using systems of quadru
pole magnetic lenses. A quadrupole magnetic lens is
This invention relates to a method and apparatus for 10 shown and discussed in “The Strong-Focusing Synchro
accomplishing the mass separation of high energy particles
tron-A New High Energy Accelertator,” by E. D. Cou
and more particularly to a method and apparatus for sep
rant, M. S. Livingnston, and H. S. Snyder, in The Physical
arating out high energy particles of equal momentum but
Review, vol. 88, No. 5, pages 1190-1196, December 1,
differing in masses.
1952. FIGURE 9 of that paper illustrates a lens of this
In high energy particles physics, it is often desirable
type. Focusing of the particles by this type of lens system
to separate out particles of equal momentum but differing
is based on the fact that all the particles making up a
in mass having energies on the order of several billion
particular beam have identical momentum, and the par
electron volts. Various proposals have been made and
ticles and mathematics of such focusing systems are well
used to accomplish such separation, including those ar
known in the art. The invention hereinafter described
rangements shown in applications Ser. Nos. 16,902, ?led 20 utilizes a focusing system of this type in which the spaces
March 22, 1960, now Patent No. 3,016,458, issued Janu
between the lenses through which the particles pass are
ary 9, 1962, and 41,708, ?led July 8, 1960. While these
subjected to electric ?elds in a manner described below in
arrangements are useful and can accomplish the desired
connection with particular con?gurations of these mag
separation, they do require the manufacture and assembly
netic focusing systems. A mathematical treatment of the
of wave guide devices in which accuracy of dimensions
principles involved in this invention is given in my article
and suitability for the exact frequencies of operation are
coauthored with E. D. Courant on “Mass Separation of
Furthermore, once the wave guides are con
structed for their particular use, it is di?icult, if not im
possible, to modify and make them suitable for other
frequencies of operation.
By the present invention, there is provided method and
apparatus for the separation of high energy particles pro
duced by accelerating devices operating in the multiple
bev. range, such as the Alternating Gradient Synchrotron
at the Brookhaven National Laboratory. The method and
construction involved in this invention utilizes standard
and well known techniques and apparatus and is highly
?exible for a wide range of applications, energies, fre
quencies, and types of particles.
High Energy Particles and Quadrupole Lens Focusing
Systems,” published in The Review of Scienti?c Instru
ments, volume 31, No. 2, pages 193-196, February 1960‘.
In order to explain how the method and apparatus of
this invention accomplishthe function of separating the
particles of di?ferent mass and the same momentum, refer
ence is made to FIGURE 1 wherein is illustrated an axis
Z-Z representing the path prior to alteration traveled by
a beam of particles to undergo separation. Disposed
along the length of axis Z-Z are a plurality of quadrupole
lens pairs M1, M2and M3, each quadrupole of each pair,
‘as is understood in the art, tending to focus the particles
passing therethrough in some particular transverse plane,
More speci?cally, the
invention involves the use of systems of magnetic lenses
such as either the X or Y planes, at right angles to each
which are used to focus the beams of particles to be
other and passing through the axis Z-Z, as is understood
separated. The systems of magnetic lenses are arranged,
in the art. Each lens pair consists of two quadrupole
in one embodiment, to cooperate with electrostatic ?elds
magnetic lenses to obtain complete focusing in all planes.
imposed between successive magnetic lenses to build up
Consider a path 12 taken by a charged particle 13 as a
over the length of the apparatus increasing transverse
result of the in?uence of lens pairs M1, M2 and M3, which
separation of the different types of particles. With the
are oriented to exert forces on particle 13 in the following
proper selection of magnetic lenses and electrostatic ?elds
manner. It will be seen that particle 13 following path 12
and a su?icient number of focusing stages, as hereinafter
intersects the Z—Z axis at places designated converging
to be more particularly ‘described, it is possible by this
points P1, P2 and P3. Particles similarly charged but
invention to obtain the desired separation.
having different directions of momentum follow paths 16,
It is thus a ?rst object of this invention to provide a
18, and 14, for example. Since the total momentum of
method and apparatus for the mass separation of high
the various particles are identical, they all pass through
energy particles.
the identical points P1, P2 and P3.
It is a further object of this invention to provide a
Should electrostatic ?elds be applied to particle 13 in
quadrupole lens focusing system in which the mass sepa
between lenses M1, M2 and M3 in the directions indicated
ration of high energy particles takes place.
by arrows A and B, it is seen that the converging points
P2 and P3 will be translated accordingly. For example,
It is still another object of this invention to focus a
beam of high energy particles having identical momenta
and to separate out the particles of different mass.
Still another object of this invention is provision for
of course, be acted upon in an opposite direction by the
same electrostatic ?eld and their node position (not
shown) would be on the other side of focal points P2 and
‘P3. Also the displacement of the point P3 from axis
handling high energy nuclear particles of equal momen
tum and obtaining their mass separation.
The exact nature of this invention as Well as other ob
jects and advantages thereof will be readily apparent from
point P2 will become P2’ for particle 13, and point P3
Will become P3’. The particles of opposite polarity will,
Z-Z will be substantially twice that of'the displacement
‘of point P2, for the effects of the electrostatic ?elds would
be cumulative.
If no electrostatic ?eld were applied to
the area between lenses M2 and M3 the new point P3’
would be the same distance below P3 as P2’ is above P2.
However, with the application of this new electrostatic
?eld, to the particles passing through point P3, the addi
tional force causes an increase in the displacement trans
verse to axis Z—Z as mentioned. Over a plurality of such
stages, the spread of the various particles will be dis
tributed in a transverse plane off axis Z——Z in accordance
with their masses. This follows because the transverse
acceleration of a particle by the magnetic ?eld force
varies inversely as the momentum whereas that due to
electric ?eld varies inversely as momentum times velocity.
Particles of given momentum but different masses have
different velocities. With proper apparatus and appropri
ately sized apertures, it becomes possible, if desired, to
pick olf particles of a speci?c mass.
A practical arrangement for accomplishing the mass
separation of particles having identical momentum and
mentioned in The Review of Scienti?c Instruments paper.
To increase separation of the particles, additional lens
arrangements of the type just described would be added on,
except that the separation to be useful must be greater
than the product of the over-all magni?cation of the lens
system and the source size 0.
It is possible to replace the lens stages required by sub
stitution using lenses known as “triplets” which focus
simultaneously in the X and Y transverse planes. A
triplet magnetic lens, as is understood in the art, consists
of three successive magnet quadrupole arrangements in
succession combined into a single unit in which the ?rst
and third lenses are opposite in polarity to the middle, or
second one, and half the strength of the central one.
It is thus seen that there has been provided a novel
method and apparatus for accomplishing the mass separa
tion of high energy particles utilizing quadrupole lens
focusing systems. It is understood, of course, that only a
preferred embodiment has been illustrated and many varia
tions of that shown may be provided utilizing these
charge is illustrated in FIGURE 2. Shown there is an
arrangement of magnetic lenses L1, L2, L3 and L4 and a
It is also understood that suitable piping apparatus under
source 0 of particles to undergo separation. In order to
vacuum for the handling of these particles will increase the
accomplish the desired separation, source 0 is located at
efficiency of the method and apparatus herein described
point f1 on the central aixs of the lens system and sepa
and that a su?icient number of stages may be added to
rated a distance from lens L1 so that all of the particles 25 accomplish the desired separation. It is also understood
entering lens L1 from source 0 will leave in the form of a
that the electrostatic ?elds, while not described particu
parallel beam 19. Thus, the focal length for lens L1, mak
ing the usual analogy to ‘optical lenses, is the distance be
tween source 0 and lens L1, hence source 0 is located at
larly, may be either constant or pulsating depending upon
the type of source utilized which may be pulsating. In
fact, the magnets, as well as the sources of the electrostatic
point f1. Lens L2 receives the parallel beam 19 from 30 ?elds, may be pulses to obtain the desired results.
lens L1 after a distance of S. The rays upon leaving
As the foregoing relates to a preferred embodiment of
lens L2 will converge at a point f2 which may be described
this invention and numerous modi?cations and alternating
as the focal point for lens L2. The beam of particles
thereof may be made therein without departing from the
crosses point f2 and enters L3 which is located from point
spirit and the scope of the invention, it is intended that the
f2 a distance equal to its focal length. Thus, the particles 35 appended claims de?ne the scope of this invention.
emerge from lens L3 in a parallel beam and after a suitable
I claim:
distance S’ the beam of particles enters lens L4. The beam
1. Particle separating apparatus for use with a source
of particles converge at the focal point f3 and continue
of highly energized charged particles of identical mo‘
on in the manner previously described. In the arrange
mentum and differing in mass, comprising, means con
ment illustrated, lenses L1, L2, L3 and L4 are each a 40 sisting of a system of magnetic lenses for receiving and
single quadrupole so that FIG. 2 illustrates one half the
focusing said particles in successive stages, and means for
arrangement required for the ?rst focusing point. At least
applying electrostatic ?elds to said particles in said lens
two focusing nodes for each transverse plane are required
system in the spaces between said lenses for effecting the
in order to obtain sufficient separation of the beams, and
distribution of said particles along transverse planes in
the electrostatic ?elds must be reversed to take advantage 45 accordance with their masses for facilitating their sepa
of the resonant effect described in connection with FIG. 1.
To obtain the desired separation of the particles in ac
2. The particle separating apparatus of claim 1 in
cordance with the principles desired in connection with
which said magnetic lenses consist of quadrupole mag
FIG. 1, four pairs of electrostatic plates 20, 22; 24, 26;
nets used in pairs rotated 90° from each other to focus
28, 30; and 3.2, 34 are mounted between adjacent lenses in
said beam of particles.
the manner illustrated and as generally understood in the
3. The particle separating apparatus of claim 1 in
art. The ?rst two sets of electrostatic plates 20-26 are
which said lens system includes two focusing nodes for
biased to exert a force on the particles emerging from
each set of lenses focusing in a transverse plane to pre
vent increase in beam width which would limit amount
indicated by arrows C and D, for a particular charge. The
of separation possible.
second two sets of electrostatic plates 28 through 34 exert
4. Particle separating apparatus for use with a source
source 0 in a direction transverse to the axis of the lens as
forces on the particles in the opposite direction along the
direction illustrated by arrows E and F. This is due to the
of highly energized charged particles having equal mo
mentum and differing in mass, comprising a plurality of
crossing of the beam of particles at focal point f2 and is
magnetic lenses for receiving and focusing particles in
designed to make the separation cumulative as previously 60 successive stages, said source being located at the focal
described. Thus focal point f2 is translated to a point
point of the ?rst of said magnetic lenses, the second of
above focal point f2 and focal point f3 is moved to a focal
said magnetic lenses separated from said ?rst lens to
point below f3. If desired, the electrostatic ?elds may be
receive the particles forming a parallel beam from said
reversed at the focal points f2 and f3.
?rst lens and focus said particles at the focal point of
It has already been noted that unless lenses L1, L2, etc. 65
said second lens, a third magnetic lens located with its
are lens pairs, focusing occurs in one plane, and defocusing
focal point coinciding with the focal point of said sec
occurs in the other transverse plane.
Thus a minimum
ond lens to receive said beam of particles, and means
complete arrangement of the type shown in FIGURE 2.
imposing electrostatic ?elds in a direction perpendicular
would be, as already noted, a repetition of the arrangement
to the axis of said lens system on the particles between
shown from source 0 to focal point f3 with focusing
said ?rst and second, and second and third lenses, re
occurring in an appropriate way in the previously de
spectively, to effect the displacement of said‘ particles
focused plane. With lenses L1, L2, etc. being lens pairs,
transverse to their beam travel in accordance with their
then a complete arrangement extends from source 0 to
point f3. The distances S and S’ are limited by the size 75
of the lenses and in accordance with the considerations
5. In a method for separating highly energized
charged particles of identical momentum and differing
ration of N times that of a single section where N sec
masses forming a beam successively ‘focused and defo~
tions are employed,
cused in a system of quadrupole magnetic lenses, the
step of imposing an electrostatic ?eld on said particles to
References Cited in the ?le of this patent
bend said particles away from the axis of said lens sys- 5
tern in accordance with the masses of said particles.
6. The method of claim 5 in which the polarity of
the electrostatic ?eld is alternated in successive sections
Hame ““““““““““““““ “ May 12’ 1959
of said system of magnetic lenses to obtain a total sepa-
Glaser —————————————— —- Dec- 29, 1959
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