Beyer ot al.: Spallation Produced Radioisotopes
Isotopenpraxis 25 (1089) I, pp. 2 - 1 0
Spallation Produced Radioisotopes for Nuclear Medical Application*)
O. J. Beyer
Academy of Sciences of the GDR, Central Institute of Nuclear Research Rossendorf, P.O. Box 19, DDR-8051
Dresden
A. F. Novgorodov, F. Itoesch
Joint Institute for Nuclear Research Dubna, Head Post Office, P.O. I5ox 79, Moscow, USSR
H. L. Bavn
CERN EP/ISOLDE, CH-1211 Geneva 23, Switzerland
Spallation reaction opens new additional possibilities for production oj a number of medical useful isotopes. In some
cases all the present world demand is produced through spallation. Because of the high transmission of targetmaterials
for medium or high energy protons lower cross-sections may be more than compensated by using massive targets. The
unspecific nuclear reaction as well as the radiochemical processing of such massivetargels lead to several difficulties. Neiv
ways for processing of large spallation targets are required. The possibilities of modern ISOL-techniques(I SOL = Isotope
Separator On-Line) for the production of medical useful radio-isotopes xcill be discussed in some detail. Corresponding
cross-section data are reviewed and discussed in relation to physico-chemical data requirements. In detail the following
radio-isotopes ivill be discussed: Sl-Bb, S2-Sr, 123-1, 167-Tm and 211-At.
Die Kernspaltungsreaktion eroffnet neue, zusatzliche Mb'glichkeiten der Herslellung einiger Isotope, die fur die Medizin
wertvoll sind. In einigen Fallen ivird der gegenicartige Weltbedarf durch die Kernspaltung gedeckt. ]Vegen der graven
Durchliissigkeit des Targelmaterials fur mittel- und holier-energetische Protonen icerden die kleineren Wirkungsquerschnitte bei Venvendung von massiven Targets mehr als kompensiert. Die unspezifische Kernreaktion als auch die
radiochemische Aujbereitung von solchen massiven Targets verursachen einige Schwierigkeiten. Es xcerden neue Wege
zur Aufbereitung von groPeren Kernspaltungstargets benotigt. Die Mb'glichkeiten der modernen ISOL-Technik (ISOL
= Isotope Separator On-Line) zur Herstellung einiger medizinisch icerlvoller Badioisotope werden im einzelnen behandell. Die entsprechenden Daten der Wirkungsquerschnitle werden kritisch besprochen und im Zusammenhang mil
den phsikalisch-chemischen Daten diskutiert. Im einzelnen werden die folgenden Badioisotope diskutiert: SI-Jib, 82-Sr,
123-1,167-Tm und 211-At.
Keywords
astatine 211; iodine 123; nuclear medicine; rubidium 81; spallation; spallation fragments; strontium 82; thulium
167
1.
In interactions of high energy protons with heavy target
elements three main typs of nuclear reactions accuro: spalI t is well known, that spallation reaction is the most convin- lation, fission and fragmentation (see Fig. 1 taken from
ient way to produce very neutron-deficient nuclei far [10]). For crossection or yield calculations for tho spallation
from the lino of beta-stability [1 — 3]. The use of intense still analytical methods basing on the work of lludstam
beams of high energy protons has been also recognized and [12] aro used. Budstam observed, that the cross-section
exploited for some timo for the production of neutron for isodiapheric nuclei grow witli increasing mass-number
deficient radioisotopes for practical application [4 — 11]. or oposit decreases homogeneously with growing mass
The main advantage of beams in the 0.5 to 1 GoV range deficiot. Consequently ho proposed an empirical exponentilies at present in high product output through an ability to al equation, which was than modified for special applicatipenetrate and induce nuclear reactions in target materials ons [13 — 15].
having thicknesses on the order of hundreds gramms per
„
„ ^.
..
, . ,
c
„ ™, ,
,
-,
,
„
Cross-sections for spallation reaction products have been
,. . -T
.
cm-. The large number of target atoms can more than com- ..
, . ., T . 1 , . „
.
°,
n i t , i
discussed at the IAEA Consultants Meeting m Vienne,
..
° .
.
pensato rfor tho generally low reaction cross sections (order
, -11O , , , „ . , . . . . T
- i n ,„ „
° ,,
. . ,,
.
April 13—15, 1981 [20]. In generall measurements of spalof 10-30m- or 10 mb) compared to the cross sections often , ..
..
. .. ..f.
,
.
f
r
. , , . , , .
,.
, .
lation cross-sections fall within a factor of approximately 2
,
,
. . ,
.
associated with lower energy reactions used in more eonc ,,
n. . , ,
T, ,
..
,
- . .•
,
of the value predicted by Budslam'a empirical systematics
, „ . .
ventional ways for isotope production.
no-i I - T .
* t
, r • , , ,,
[12] which seems to be sufficient for the moment. Optimiz*) Paper presented at the IAEA Consultants Meeting on "Data a t i ° n ° f t a r g e t " a n d s e P a r a t i o n techniques are of similar
Requirement for Medical ISadio-Isotore Production" Tokyo, April importance. It is the aim of this paper to discuss tho produ20-24, 1087, Japan
ction of medical isotopes via spallation as a complex probo
*
Introduction
Isotopenpraxis 25 (19S9) 1
Beyer et al.: Spoliation Produced Radioisotopes
100FT
-
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100
150
M A S S — N O M 13 E R.
Vis. I
It is our suggestion, that new separation techniques could
solve some of the problems and open possibilities to produco
valuablo spallation radioisotopes in a more sufficient way.
Today now rapid separation methods based on thormochcmical and physical principles allow radioactive nuclei
of allmost all elements to bo contineously transferred from
an accelerator irradiated target into an ion beam. These
techniques often referred to as target ion-source system
have- in tho last 20 years turned on-line mass separators
into tho most efficient tool for production and study not
only of nuclei far from stability but radioactivo nuclei in
general [23]. Tho principle of such an ISOL-system is
shown in Fig. 2. For more genornll information see [1 — 3].
Tho production, transport and separation processes in
such an integrated ISOL-system can bo devided into tho
following main steps:
Mass distribution for reaction products formed in interaction
Ta with protons of different energies (taken from [lfi])
of
lem of tho nuclear reaction and chemical or physical principles of separation techniques.
Tho long range of the high energy protons permits tho
simultaneous irradiation of stacked thick targets as well
as tho uso of a singlo massivo target. The advantage is that
several radioisotopes are availablo in both cases simultaneously. But this advatago is also an disadvantage because
of tho formation of isotopic impurities. This problem must
bo handled through optimized choices of irradiation and
decay periods as demonstrated in tho caso of 123-1 via
123-Xo [17, 18]. Tho plethora of waste and by-product
radioolcmontstobo dealt witharo other complicating factors.
Nevertheless practically all tho present world supply of
82-Sr and C7-Cu and good fractions of 127-Xo, 109-Cd and
08-Go aro produced via spallation reaction [0, 7, 11, 19].
Formation of the products in interaction of an intense
proton beam of around 700 MoV
Diffusion of the product nuclei from the interior to
tho target surface
Desorption from the surface
Transport of tho product to an ion-source
Ionization of tho product
Mass-separation of the products.
For a completo description of the processes we need to
know about tho following data'(othors than nuclear data):
— Diffusion coefficients
— Adsorption enthalpies
— Ionization behaviour.
High temperature diffusion
The solution of tho second Fich law
dc
lit
drc
•
(1)
dx2
= 100
800 °°
E
r
1
(2n
X exp —
THE PRINCIPLE OF ON-LINE MASS SEPARATION
Proton or helium beam
Selective target
and lonsource system
Monolsotopic ionbeams are
directed to the experiments
via 4 external
beamlines .
i'ig. 2. The principle of on-liuc mass separation
lEotopeupraxis 25 (l'JSD) 1
Acceleration of singly
charged Ions to 60keV
(2)
F
Beyer ot al.: Spallation Produced Radioisotopes
Fi?. 3. Release of some spallation reaction
products from 0.1 mm thick Zr-foils irradiated with CGO JleV protons (release time 10 min)
[20]
1000
1400
1600
Temperature
1800
2000
(K)
describes tho relation of fractional release (F) of a given EA for tho diffusion process can be obtained from an Arnuclear reaction product, tho diffusion coefficient (D) and rhenius plot according cqu. (3).
the target-foil thickness (cZ) [24]. This equation (2) is applicable for tho special samplo conditions: foiles or plates whoro
(3)
o 1 1{T>
tho foil-thickness d is small compared to tho length and
width ( ( i ^ o a i ) and with homogeneous distribution of whore It is tho gas-constant.
the diffusing particles throughout tho matrix. The experiSystematical studies have been performed in tho followmental value F can bo transformed into diffusion coef- ing manner: target foils of refractory metals were labelled
ficients using tho tables oiZimen [25]. Tho activation energy homogeneously with radio tracers by irradiating them with
CGO MoV protons. Sampols of tho irradiated foils were annealed in high vacuum at high temperatures. Tho samples
T e m p e r a t u r e (°C )
wore analyzed beforo and after heating by means of gamma1500
1200
1000 900
2000
spectroscopy for determination of the fractional release of
-6
spallation reaction products. Tho results aro published for
tho following target elements: Ti [2G, 33], Zr [20, 27], Nb
-7
—
[28], Mo [29], Hf [30], Ta [31], W [32], Re [33], Ir [33],
Th [33], For illustration a few results aro presented in
Figs. 3 - 0 .
Tho diffusion relase studies may bo summarized in tho
following way:
i.
-14
For example Y diffuses faster than Sr, which is
faster than Rb (sco Fig. 3). The reason for this sequence is tho decreasing radius of the diffusing
particles.
Tho diffusion coefficient for a given trace element
decreases for different host metals in-the following
sequence:
-1-14
. 4. Arrhe7iius-plot for tho diffusion of Sr in polycristalline Zr [2C]
•D
55
2000
2200
2400
T E M P E R A T U R E
In a given host metal of tho IV B, V B o r V I B group
of tho periodic table tho diffusion coefficients for
trace elements grow in the following sequence:
D\u\ •
IVB
/100/Um
2600
( K )
2800
Fig. 5. Help use of Y from ilo-foils of different
thickness irradiated with CCO MeV protons
(annealing time 5 min) [29]
Isotopenpraiis 25 (19S9) 1
_i
Beyer et nl.: Spnllation Produced Kadioisotopes
'I,
19
1 8
ionic radius
( A )
covalent radius
•
I
1
( A )
24
1.5
14
2 2
,\
IV
\
A
Yb
•c
2.3
\
1.6
Tm
Lu
:o
200D-
K
uoo-
• \
\
\
2 1
;i
\
; •
.(
•1
\
•1
•1
.
I
\
19
1.2
I I
l
1.1
\ \
•
1
*
\
\
t
"
\
\
^*
'
*
"
*
•
•
«
H00-
tt
_
1200-
>1
A
• \
i
1.0
1600-
' • • • - . . . . .
2.0
.: \I
13
30
1.8
10
r
1.7
j \
.'. V.
1.6
•
1000-
0
1 S
\
b
B
7
Gd
Ig D
TmSm
PrtfCe
Eu+Yb+Sr
-8
M ) MO - Ampu II •
0
igD
--9
-9
-10
Sr Zr
Rb Y
Cs La Pr Pm Eu Tb Ho Tm Lu
iv.
For oxamplo Y diffuses fastest in Zr and in Nb faster
than in Mo. Comparo Figs. 3 and 5. Tho reason for
this effect is the growing lottico density of tho host
metals.
In a given host metal tho elomonts of one group of
the periodic tablo diffuse according to growing
atomic masses: Sr diffuses faster than Ba in Ta
(seo Fig. G).
From tho systematical study ono can evaluate, that
all rare earth elements diffuso in metal matrixes as
JM3+-particles, tho I I A-eloments as M2+, tho alkaline
clments as M+ and tho nobel gases as neutrals (seo
Fig. G and Fig. 3).
Surface effects
In our roleaso studios wo found that in Ta tho diffusion
of tho raro earth elomonts is more rapid than of Ba followed
by Cs. For tho desorption from tho surface the sequence is
reverse with Cs being fastest followed by Ba, lanthanoides
Isotopenpraxis 25 (19S9) 1
Hitiaichilo
0
ll.Rlhil
c
Ba Ce Nd Sm Gd Dy Er Yb Hf
In generall ono can conclude that solid phaso diffusion
processes very often aro fast in order to uso refractory
metals as high tomperaturo targets. A largo number of
other refractory materials such as mctaloxidcs, borides,
carbides as well as molten metals and alloys has been
investigated to dc velopo suitablo targotsystcms for ISOLDE
(review papers seo [61, GO, 44]).
3.
H l l i r g i t
Q
-10
Fig. G. Diffusion coefficients of spallation reaction products in polycristalline Ta (lower part) in comparison with the atomic and
ionic radii of the diffusing particles (upper part). Ta-foils of
83 tun thickness were irradiated with 660 JIcV protons. Tho
diffusion coefficients were determined for the indicated elements
simultaneously from release studies, tho annealing temperature
was 2750 K, annealing time 300 s. No significant difference hi the
diffusion behaviour of the rare earth elements has been observed,
they all diffuse faster then Sr and Ha
iii.
H a l l k •> hod«
(?)
0
5
6
7
8
9
10 c m
Fig. 7. Thermoehromatographical separation of carrier free rare earth
radio isotopes in vacuum. The rare earth radio nuelidcs are formed in spallation reaction irradiating n Hf-target (3) with GOO Mel
protons. The Hf-target was inserted into 3Io-crucibIe (1) carriing
a thermochromatographic Ta-tube (5). Tito crucible containing
the target was heated to 2170 IC by electron bombardment (2).
All rare earth radio isotopes are released and adsorped according
theire adsorption energies along the Ta-tubc. Everage annealing
time was 10 min [30, 3iJ
and Hf. Thus in a Ta-powder target tho rare earth elements
will bo delayed compared to Cs and Ba duo to tho largo
total surface. Consequently from a Ta-foil target with
optimized foil thickness tho raro earth elements will bo
released moro rapidly because tho surfaco is deminished.
Tho surfaco adsorption behaviour or in other therms tho
adsorption enthalpies play an important rolo in tho release
of nuclear reaction products from a target as well as for tho
transport of tho products in the gas phase.
Desorption studies for rare earth elements liavo been
performed in a similar way as tho release studies [34]. Fig. 7
illustrates tho possibilities to uso differences in tho adsorption enthalpies for thermochromatographic separations.
A systematical study of tho adsorption of trace metals
at metallic surfaces base recently been published by Roesch
Beyer ot nl.: Spallation Produced Radioisotopes
and Bidder [35]. The wide variation of the surface material,
the composition of the used carrier gases, variation of the gas
preasuro and temperature opens the wide range of separation techniques starting from gaschromatography over
gasthermochromatography and thcrmochromatography to
vacuum thermochromatography.
(i.
In this chapter wo like to illustrato the possibilities of the
discussed techniques for the production of somo of the
most important medical radioisotopes via spallation route.
6.1.
1.
lonization
A selective ionization is a modern radiochemieal separation
technique. For the production of radioisotopes via spallation
the- following ion-source principles arc suitable to he operated in an integrated target ion-sourco system:
i.
ii.
iii.
iv.
v.
5.
Positivo surfaco ionization ion-sourco with Taionizer kept at 1300 K for selective ionization of tho
alkaline elements K, Rb, Cs and Fr [30]. The ionization efficiency is of tho order of 90%.
Positivo surfaco ionization ion-source with W-ionizer
(or Ro) at high temperatures (2700 ... 3000 K) for
ionizing tho lanthanoidcs, In, Ga, Sc, Al, Ca, Sr, Ba,
Li, Na and Tl. Tho ionization efficiency varies from
a few % up to 80% [30, 37, 38].
Negative surfaco ionization ion-source with LaB6ionizer for selectivo ionization of Cl, Br, I and At.
Ionization officiences of up to 40% have been obtained [30, 39].
The plasma discharge ion-sourco with cooled lino at
300 K and ionization temperatures around 1300 K
is used for selectivo ionization of nobel gases. Efficiences archieved for He, Ar, Kr, Xo and Rn aro
0.5%, 2%, 5%, 15%, 30% and 40% respectively
[36]. A similar sourco with a cooled line kept at
700 K is used to ionizo tho volatilo elements of tho
groupIIBZn, CdandHgwithcfficionccsof 10 ... G0%
[36].
A high temperature version of tho plasma dischargo
ion-sourco (lino at 220 K) is intended to ionizo tho
less volatile elements from group IB, I I I , IV and V.
This ion-sourco can bo used in conjunction with
CF4 to form volatilo fluorides of tho mentioned elements [30].
Chemical selectivity
As mentioned tho product mixturo of a massivo target
irradiated with protons with Ev 0.5 GoV is rather complex.
Tho difficulties to handlo such targets and product mixtures can be compared with tho fission product mixturo in
isotopo production plants only. Nevertheless chemical
selectivity can bo obtained using tho above mentioned
techniques by ono or several of tho following means:
i.
ii.
iii.
iv.
Solectivo release from tho target (Sr from Zr [40]).
Selectivo adsorption of unwanted species at suitable
surfaces (sclctive release of Yb from Ta-powder [33])
or selectivo transport of tho required product (52Fo
from Ni [41]).
Selectivo ionization.
Mass-separation of molecular side bands (iodine as
All+-particles [30]). Isobaric separations using differences in tho adsorption enthalpies [42]).
ISOL-tccliniquo for production
of medical isotopes via spallation
Sl-Iib
Becauso of the short halflifo thcro is no much sonso to
produco 81-Rb via spallation, but tho isotopo separator
opens tho way to produce a now typo of 81-Rb-81m-Krgenerator. 81-Rb is best produced at ISOLDE using a
Nb-powder target with yields of 3.8 • 1010 atoms per second
for 1 f*A proton beam current (Figs. 8, 9 [44]). This production rato corresponds to 1.0 MBq/^As (or 20 mCiin 7.7 mill
collection timo for 1 [*A proton beam current). By implanting the 81 -Rb+-ions into mylar foils (or other plastic material liko polyethylene etc.) an implantation type of 81-Rb81m-Kr-generator is obtained. Tho 81m-Kr can bo oluted
nearly quantitatively by blowing air over the implanted
Rb-sourco as well as by olution with isotonic saline solution
suitable for direct infusion [43]. No 81m-Kr-elution will bo
achieved by using motallic foils as implantation backing.
Tho 81-Rb break through is as lowas in conventional 81Rb-81m-Kr-gencrator systems. Tho implantation typo
generator could bo realized of oxtromly small sizo sinco for
an implantation density of 1014 atoms/cm2 less then 0.5cm2
foil area is required to make a 800 MBq (20 mCi) generator.
Tab. 1. Hcvicw of spallation rcction cross-section data for t h e radioisotopes discussed in this paper. Tlic proton energy was limited
to t h e 500 MeV region
Ifadionuclicle
82-Sr
S5-Sr
123-Xc
125-Xe
127-Xc
123-1
1G7-Tm
lCS-Tra
211-Kn
211-At
Target
Zr
Xb
Mo
Mo
Mo
ltblir
Mo
Mo
La/Cu
La/Gu
I
Cs
Ba
La
La/Cu
La/Cu
1
Cs
Da
La
La/Cu
La/Cu
La/Cu
Ln/Cu
La
Lu
Ilf
Ta
Lu
Hf
Ta
W
TIi
Til
U
KP
[McV]
Cross-Section
590
590
590
SOO
800
800
SOO
SOO
590
590
CCO
CCO
COO
COO
590
590
COO
KCO
COO
6G0
590
SOO
590
590
SOO
590
590
590
5'JO
590
590
590
590
CCO
fiCO
CCO
19 ± 4
22 ± 4
15 ± 3
24.5 ± 0.S
23 ± 1
2.1 ± 0.2
•IS ± 0.7
.50 ± 2
3G ± 5
45 ± G
3.S ± 0.1
29.3 ± 1.7
2G ± 4
31.9 ± l.C
57+9
43 i 9
C.G ± 0.5
45 ± 0.5
38 ± 0
47.7 ± 3.0
53 ± 11
51 i 7
57 ± 0
57 ± 9
51 i 3
50 ± G
.11 ± 10
49 ± 7
49 ± 7
5 ±1
G ±2
0.8 ± 0.4
0.4 ± 0.2
13 ± C
13.2 ± 2.2
5.2 ± 1.4
Tlct.
[ l C m 1 =mb]
53
53
53
5C
40
54
•JG
50
53
51
IS
18
IS
IS
53
54
IS
18
18
18
53
5G
54
03
50
58
53
5S
53
58
58
58
58
03
G4
G4
Isotopenpraxis 25 (19S9) 1
Beyer ot al.: Spallntion Produced Radioisotopes
VALVE
TRANSFER
LINE
LINE AND
IONIZER
CURRENT FEED
VACUUM
CONTAINER
Fig. S. Scheme of target ion source system
tor the ease of a surface ionization ion
source. In addition the extraction electrode
is shown fixed to the acceleration chamber,
(taken from [U])
ed. Tho cross-contamination for routine practical uso is
allmost less then 0.1% in this mass region. Recent studies
Recently tho comploto probloms about S2-Sr-82-Rb-gcne- at CERJST demonstrated, that a Zr-foil target could withrators havo been published [45]. Tho cross-section for tho stand a well focused proton beam of 100 y.A [50]. It is
formation of S2-Sr in Mo irradiated with 800 MoV protons expected to obtain 1010 atoms 82-Sr per 1 [xAs or 1010 Bq/
is (2.3 ± 0.1) • lO"30 m-(23 mb) and for S5-Sr (4.8 ± 0.7) • 1000 [zAh (10 h, 100 (*A). Tho advantage of this technology
10-so ,n2 (43 m b) [40] (Tab. 1). Tho radiochomical proce- is first tho high isotopio purity; secondly practically no
dure has been modified several times [47, 48, 48]. High liquid wasto is produced. The disadvantage is that no other
dose rates of tho irradiated targets (107 R/h in 1 cm distance product as 77-Br or 88-Y are available simultaneously from
[48]), largo amounts of process solutions and unsatisfied
the same target.
purity of tho final 82-Sr-preparation were tho main probloms in tho wet radichemical process [48, 49]. Tho isotopic
byproduct 85-Sr romains still a serious problem. At EOB
6.3. 123-1
an overago isotopic ratio 82/85-Sr of only 1.0 to 1.2 is
obtained depending on irradiation time. During the clinical Special interest was directed to the production of radiouso of tho generator the 85-Sr grows up to an excess of a xenon via spallation [18, 20, 51]. It has been demonstrated,
few 100% compared to tho 82-Sr activity. It was allready that by optimized choice of irradiation and decay periods
proposed to solve this problem by using an isotope separa- ruthcr pure 123-1 could bo obtained. Also important was
tor [48].
tho possibility to produce 125-1 and 127-Xo simultaneously.
Wo recommend to uso additional ISOL-target technique. From a 175 g CsCl-target after 4 h irradiation and 4 h
From a 50 g/cm2 Zr-foil target (foil-thickness up to 0.5 mm) grow up period for 123-1 via 123-Xo decay 850 mCi 123-1
tho Sr is released rather selective at 1750 K (Fig. 3). A with 0.4% 125-1 contamination is obtained [52]. Tho 127high tomperaturo surface ionization ion-source could give Xe produced via spallation at TRIUMF from 0.8 cm thick
an ionization yield of bettor then 50%. At tho collector of CsCl-pellot contains 15% of 129m-Xo and 12% 131m-Xo
nn isotope separator pure 82-Sr and 85-Sr could bo collect- [11]. Cross-section data are summerized in Tab. 1.
6.2. 82-Sr
Isotopenpraxis 25 (1989) 1
Beyer ot al.: Spnllation Produced Radioisotopes
Tho 125-1 contamination in spallation produced 123-1
preparations presently is higher than those for tho (p, 5n)production route. Ono possibility to solvo this problem is
tho application of ISOL-teclmiquo. From a molten Latarget kept at 1770 K Cs is released fast and transported
to a surface ionization ion source [57, 30]. This combination
is highly selective for Cs. Tho total efficiency is of tho order
of 80 ... 90%. Tho Cs-yiokl courvo is shown in Fig. 10 [44].
Tho yield as well as tho activity of the corresponding products aro as follows:
Rubidium (37-1)
10'
10'
10
Cs-isotope
10
°10
6
123-Cs
123-Cs
127-Cs
L
a
Q-
5
yield
[atoms/iiA]
product
5.0- 10"
1.1 • 10"
1.3 • 10"
123-1
12J-1
127-Xc
yield
[Bq/sl
[mCi/li]
7.3- 10'
1.4- 10'
2.9- 10«
71
1.S
2.8
« 10
Noto that theso activities aro obtained for 1 [iA proton
beam intensity only. Tho molten La-targct of tho given
design could withstand a beam current of 50 [xA [50]. From
this figures ono can easy estimate: the system is able to
produco multi-Ci quantities of 123-1 and allmost Ciquantities of 125-1 and 127-Xe simultaneously within a
few hours. The isotopio impurities are determined from tho
mass-resolution of the isotope separator. Tho 125-1 contamination in tho final 123-1 preparation will bo of tho order of
10
10
10
10
60
65
70
I
80
75
Rb Mass
85
90
95
6.4.
Fie. 9. Yield curve for the production of Rb-isotopcs at ISOLDE from
a 50 B/cm' Nb-po\vder target taken from [14]
Caesium (55-1)
' 1 ' ' '' i ' • ; ' T
10
10
10
10
Tho isotope 107-Tm is suitable for scintigraphic in vivo
studies [59]. The best way to produco 167-Tm is via spallation reaction [58, 59]. The most elegant way would be the
application of ISOL-techniquc. As allready mentioned a
Ta-powdcr target givo highly selective Yb-isotopes [00],
tho other rare earth elements arc discriminated by surfaco
effects. A Ta-foil target connected to tho samo ion-sourco
produces isobars of tho rare earth elements [33] (Fig. 11).
«
9
1U
8
109
6
108
5
107 -Pr
*
o.
a 104
o
•< 10
10
33
0)
^ /
/
/
6I
10
Pm
/k
M
/
/
"
1
"
' 1 ' ' ' '
1
" *i ' "•
*
*
2
•
CL
. 1 ...... i . . . .
115
fo\.
Ho
/ /
1 Er
I
-
\
1
Dy
-
10* -
-
103 -
-
IO2 -
-
101
'
if
0
t
10
110
i l l
Eu G d
105
/
/ / / Ho/ 1 Y
/Tb / / T " > / \ /
/
> •
3
10
"
Smi
7
101
L
O
1• • • • • • " • 1
io 1 0
duct ion
0
' '1 ' ' ''
IS
1G7-Tm
120
125
1
130
Rare earths from Ta-foil
-
1 ..
135
140
145
Cs Mass
Fig. 10. Yield curve for the production of Cs-isotopes from a 140g/cm :
molten La target and a 1 nA GCO JleV proton beam in 1 s
(taken from [44])
130
140
150
160
170
Mass number
Vig. 1). Production yields of lanthanoid isotopes from a 122g/cm'
Ta-foil target connected to a positive surface ionizer. Individual
measurement points are not indicated, (taken from [33])
Isotopenpraxls 25 (1989) 1
Beyer ot al.: Spallntion Produced Radioisotopes
Tho production rato for 107-Yb is 1.1 • 1010 atoms/s and
|xA proton beam intensity. This gives n. practical production yield for 1G7-Tm of approximately 1 mCi/jiAli. Tho
Ta-foil target of tho given design could bo irradiated with
100 (xA proton beam curront [50].
[11] It. Robertson, I). Graham, I. C. Travcna, "Radioisotope Production
via 500 MeV Proton-induced Reactions" Third Int. Snip, on Radiopharmaceutie.il Chemistry, .luelich (FRG) 19S2
[12] G. Itudslam, Z. Naturforsehuiig 21a (19CC) 1027
[13] A. K. Lairukhina, It. I. Kuznelzora, JINR 0-1751) llubua 19C9,
pp. 125 (in Russian)
[14] E. Hupp, T. Fcncs, "Cross-sections for the formation of spallation
products using CGO McV protons", JINII G-499S, Dubua 1970 (in
6.5. 211-At
Russian)
[15] 31. E. Schilacci, LASL Report MPDOT/MES-I, 1970
In similarity to 123-1 tho medical important 211-At [1C] U. Trabilzseh, K. Bucehmann, Radiochimiea Acta 10 (1971) 15
(radionuclido therapy) can be produced with satisfied iso- [17] / . Huzar, 11. Loeofe, "Production of Cyclotron Isotopes for Medical
Purpose at SIN/KIR", Physics Report No. 3, p. 139 (19S1), Swiss
topic purity via tho 211-Rn [02]. Tho cross-sections for tho
Inst. for Nucl. Res. Villigcn, Switzerland
formation of 211-Rn as well as for 211-xVt from uranium [18] 31. AdiWish, C. G. Chumin, V. A. Khalkin, O. Knolck, 31. Ja.
aro significant smaller than for thorium as target [65]
Kttznetsova, Ju. V. Xorcccv, V. I. Fominykli, A\ G. Zaitseva, Int.
J. Appl. Radiat. lsot. 31 (19S0) 103
(Tab. 1). ISOL-techniquo can bo used to produce 211-At
via tho mother-nuclido in a very elegant way. ThO2 or [19] C D. Hoffman, "Isotope and Nuclear Chemical Division, Annual
Report FY 19S3 Oct. 1982-Sept. 19S3" ed. by J. II. Heikcn and
ThC2 targets [01] are connected to a plasma discharge ion
/ / . A. Lindbcrg LA-10130 PR Progress Report UC-4 May 1984
9
source with cold lino [30]. Practical yield of nearly 10 211- [20] / / . A. O'Brien Jr., "Tables o£ spallation cross-sections" Paper
Rn atoms per second and \xA. proton beam intensity havo
presented to the IAEA Consultants Meeting on Nuclear Data for
Medical Radioisotope Production held in Vienna, April 1 3 - 1 5 ,
been obtained [01, 30].
19S1
[21] G. G. Jonsson, K. Lindgrcn, Pliys. Scripta 7 (1973) 19
[22] G. G. Jovsson, K. Lindgrcn, Phys. Scripta 15 (1977) 308
[23] II. L. Itain, "Radioactive Ion-beams available at on-line Mass
7.
Conclusions
Separators", CERN-EP/SG-12S, 12. Sept. 19SG, Proc. 11th Int.
Conference on Electromagnetic Isotope Separators and Techniques
related to Their Application Los Alamos, N. M., August 18—22,
i. Spallation reaction is a very suitable routo for production
19S6
of somo medical radioisotopes. Because of tho limited
[24] J?. 31. Barrcr, "Diffusion in and through solids" (E. K. Iiideal, cd.).
number of corresponding accelerators as well as because of
New York: Macmilian Co. 1911
the priority of experiments at such facilities a regular sup- [25] K. E. Zimen. ,,TabelIen zur Aiiswertung dcr Messungen der Diffussion radioaktivcr Gasc" IIMI-B 10 (19G2)
ply of shortlived isotopes like 81-Rb or 123-1 produced in
this way scorns to bo unrealistical. For longlivcd isotopes [2G] G. J. Beyer, A. F. Novgoroilov, "Tracer Diffusion einiger Spallations-Produktc in polykristallincm p-'/.r und jS-Ti", ZfK-328 Rossenhowever a fow production runs per year will be sufficient
dorf 1977
to organize a regular supply.
[27] A. F. Xovgorodov, G. J. Beyer, A. S. Koralcv, "Tracer-diffusion of
spallation products in polycrista'.linc ^-Zirconium" (in Russian) •
ii. Stablo impurities in tho targetmaterial, isotopic
JINR C-12113 Dubna 1070
impurities duo to tho lack of reaction selectivity, waste
[28] G. J. Beyer, A. F. Korgorodoi:, Radiocliem. Radioanal. Letters 27
problems and others aro tho main complicating factors in
(1970)341
radiochomical processing of largo spallation targets. ISOL- [29] G. J. Beyer, A. F. Xovgorodoi; "Tracer Diffusion einiger Spallationsnuklide in polykristallincm Molybdaencn", ZfK-317 Rossentechniques open now ways in spallation radioisotopo producdorf 197G
tion and application. Isotope separation teehniquo itself
J. Beyer, A. F. Novgorodov, "Tracer Diffusion einiger Kernis also useful to bo applied in "classical" Ill-production to [30] G.
realctionsproduktc in Hafnium-Metal", ZfK-303 Rosscndorf 1970,
improve tho isotopical purity.
JINR PG-991G Dubna 197G (in Russian)
iii. Modern physico-chemical data aro of samo rolevanco [31] G. J. Beyer, W. I). Fromm, A. F. Xorgorodoi; Nucl. Instrum.
Methods 140 (1977; 419
as nuclear data in radioisotopo production. By knowing
[32] G. .1. Beyer, A. F. Norgorodov, "Tracer Diffusion ciuiger Kernrcakdata for release, surface adsorption and ionization ISOLtionsprodukte in Wolfram", ZfIC-310 Rosseudorf 197G
tcchniquo is a suitablo tool to determine simultaneously [33! T. Bjornslad, E. llvgelo, P. Iloff, O. C. Jonsson, E. Kvglcr, II. L.
Itacn, S. Sundcit, B. Vosicki, "Recent developments of higli tempecross-sections.
rature metal targets for ISOLDE", CERN-EP/8G-130 Sept. 1980,
Received July 17, 1087
Proc. 11th Int. Conference on Electromagnetic Isotope Separators
and Techniques related to Their Application, Los Alamos, N. 31.,
August 1 8 - 2 2 , 1980
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[6] / / . A. O'Brien, A. E. Ogard, P. 31. Grant, "Radioisotopes from a
Aug. 1980; II. Kircliner, "An ion-source with bunched beam release",
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GSI-80-28 PREPRINT Aug. 19SG
Physics Radioisotope Programe" LA-Report 74-1203
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Osman/Zaky. Structuro of 8Bo
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Isotopenpraxis 25 (1989) 1, pp. 1 0 - 1 5
Structure of 9Bc Nucleus Using the Generator Coordinate Method
and the Three-Body Model
A. Osman, M. Zaky
Cairo University, Faculty of Science, Physics Department, Cairo, Egypt
The structure of the "Be nucleus is considered as being composed oj three clusters (two alpha particles and a neutron).
The bound state of the 9Bc nucleus is studied using the approaches of the generator coordinate method as well as the
three-body model formalism. The numerical calculations are carried out \tsing different types of two-body interactions.
Yamaguchi, Gaussian, Tabakin and Volkov type potentials are used. The three-body model is also used in treating the
three clusters forming the 9Be nucleus by following the Faddeev formalism. In both approaches, the low-lying energy
levels of the aBe nucleus as well as its binding energy are numerically calculated. Good agreements are obtained between
the present theoretically calculated values and the experimental data.
Die Struklur des 9Be-Kerns wird als ein Cluster aus drei Teilchen betrachtet (zwei a-Teilchen imd ein Neutron). Der
gebundencZustand des 9Be-Kerns wird unter Anwendung der Methode der erzeugenden Koordinaten und des DreikorperKernmodcll-Formalismus untersucht. Die numerischen Bcreclinungen wurden mit verschiedenen Zweikorper-Wecliselloirkungen ausgejuhrt, wobei Yamaguchi-, GauP-, Tabakin- und Volkov-Potentialcn verwendet werden. Das DreikorperAlodell wurdc auch bei der Behandlung des Dreiteilchen-Clusters angewendet, das den 9Be-Kern nach dem FaddeevFormalismus bildet. Fur beide Naherungen wurden die tiefliegenden Energieniveaus des *Bc-Kerns und Hire Bindungsenergicn humcrisch bcrechnet und es konnlen befriedigende Ubcreinstimmungen zwischen den berechneten und den experimentellen Daten crzielt werden.
Keywords
beryllium 9; cluster model; faddeev equations; generator-coordinate method; lippmann-schwinger equation;
nuclear models; nuclear structure; three-body problem
1.
Introduction
Tho nuclear structuro of light nuclei have been shown as
one of tho important tools for extracting some static properties of these nuclei. Tho nuclear shell model has been extensively used in an attempt to explain certain features of
light nuclei. Tho shell model calculations lead to the result
10
that both of tho L-S and J-J coupling schemes do not givo
an adequato explaination of tho relevant experimental
data. The intermediate coupling in tho p-shell for all nuclei
has been extensively calculated and have boon shown that
tho energies of almost all known low-lying levels are reproduced satisfactorily with good agreement with tho
experimental magnetic moments, Ml transition probabiliIsotopenpraxis 25 (1989) 1