Eur. Phys. J. Special Topics 207, 1–117 (2012)
c
EDP Sciences, Springer-Verlag 2012
DOI: 10.1140/epjst/e2012-01599-9
THE EUROPEAN
PHYSICAL JOURNAL
S
PECIAL TOPICS
Review
Storage ring at HIE-ISOLDE
Technical design report
M. Grieser
1
, Yu.A. Litvinov
2,3,a
,R.Raabe
4
,K.Blaum
1,2
, Y. Blumenfeld
5
,
P.A. Butler
6
, F. Wenander
5
, P.J. Woods
7
, M. Aliotta
7
, A. Andreyev
8
, A. Artemyev
2
,
D. Atanasov
9
,T.Aumann
10,3,a
, D. Balabanski
11
,A.Barzakh
12
, L. Batist
12
,
A.-P. Bernardes
5
, D. Bernhardt
13
,J.Billowes
14
,S.Bishop
15
,M.Borge
16
,
I. Borzov
17
,F.Bosch
3,a
, A.J. Boston
6
, C. Brandau
18,19
, W. Catford
20
, R. Catherall
5
,
J. Cederk¨all
5,21
, D. Cullen
14
,T.Davinson
7
, I. Dillmann
22,3,a
, C. Dimopoulou
3,a
,
G. Dracoulis
23
,Ch.E.D¨ullmann
24,25,3,a
, P. Egelhof
3,a
,A.Estrade
3,a
,D.Fischer
1
,
K. Flanagan
5,14
, L. Fraile
26
,M.A.Fraser
5
, S.J. Freeman
14
, H. Geissel
22,3,a
,
J. Gerl
10,3,a
, P. Greenlees
27,28
,R.E.Grisenti
29,3,a
,D.Habs
30
,R.vonHahn
1
,
S. Hagmann
29
, M. Hausmann
31
,J.J.He
32
,M.Heil
3,a
,M.Huyse
4
,D.Jenkins
33
,
A. Jokinen
27,28
,B.Jonson
34
, D.T. Joss
6
,Y.Kadi
5
, N. Kalantar-Nayestanaki
35
,
B.P. Kay
33
,O.Kiselev
3,a
, H.-J. Kluge
3,a
,M.Kowalska
5
, C. Kozhuharov
3,a
,
S. Kreim
1,5
,T.Kr¨oll
10
, J. Kurcewicz
5
,M.Labiche
36
, R.C. Lemmon
36
,
M. Lestinsky
3,a
,G.Lotay
7
,X.W.Ma
32
, M. Marta
3,a
, J. Meng
37
,D.M¨ucher
15
,
I. Mukha
3,a
,A.M¨uller
13
, A.St J. Murphy
7
, G. Neyens
4
, T. Nilsson
34
, C. Nociforo
3,a
,
W. N¨ortersh¨auser
24
, R.D. Page
6
, M. Pasini
5
, N. Petridis
29
, N. Pietralla
10
,
M. Pf¨utzner
38
,Z.Podoly´ak
20
,P.Regan
20
, M.W. Reed
20,23
,R.Reifarth
29
,
P. Reiter
39
, R. Repnow
1
, K. Riisager
40
,B.Rubio
41
,M.S.Sanjari
29
, D.W. Savin
42
,
C. Scheidenberger
22,3,a
,S.Schippers
13
, D. Schneider
43
, R. Schuch
44
,D.Schwalm
1,45
,
L. Schweikhard
46
, D. Shubina
1
, E. Siesling
5
, H. Simon
3,a
, J. Simpson
36
, J. Smith
8
,
K. Sonnabend
29
,M.Steck
3,a
, T. Stora
5
,T.St¨ohlker
47,48,3,a
, B. Sun
37
, A. Surzhykov
2
,
F. Suzaki
49
,O.Tarasov
31
,S.Trotsenko
48
,X.L.Tu
32
, P. Van Duppen
4
, C. Volpe
50
,
D. Voulot
5
, P.M. Walker
5,20
, E. Wildner
5
,N.Winckler
1
, D.F.A. Winters
3,a
,
A. Wolf
1
,H.S.Xu
32
, A. Yakushev
3,a
, T. Yamaguchi
49
,Y.J.Yuan
32
, Y.H. Zhang
32
,
and K. Zuber
51
1
Max-Planck-Institut f¨ur Kernphysik, 69117 Heidelberg, Germany
2
Ruprecht-Karls-Universit¨at Heidelberg, 69120 Heidelberg, Germany
3
GSI Helmholtzzentrum f¨ur Schwerionenforschung, 64291 Darmstadt, Germany
4
Instituut voor Kern- en Stralingsfysica, KU Leuven, 3001 Leuven, Belgium
5
CERN, 1211 Geneva 23, Switzerland
6
Department of Physics, University of Liverpool, Liverpool L69 7ZE, UK
7
School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, UK
8
University of the West of Scotland, Paisley PA1 2BE, UK
9
Faculty of Physics, St. Kliment Ohridski University of Sofia, 1164 Sofia, Bulgaria
10
Institut f¨ur Kernphysik, Technische Universit¨at Darmstadt, 64289 Darmstadt, Germany
11
Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 1784
Sofia, Bulgaria
12
Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia
13
Institut f¨ur Atom- und Molek¨ulphysik, Universit¨at Gießen, 35392 Gießen, Germany
14
School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK
15
Physik Department E12, Technische Universit¨at M¨unchen, 85748 Garching, Germany
a
The members of the GSI Helmholtzzentrum f¨ur Schwerionenforschung will exploit the synergies
with the FAIR physics program and concentrate on R&D activities relevant for FAIR.
2 The European Physical Journal Special Topics
16
Instituto de Estructura de la Materia, CSIC, 28006 Madrid, Spain
17
Centr Jadernykh Dannykh, Fiziko-Energeticheskij Institut, 249033 Obninsk, Russia
18
ExtreMe Matter Institute EMMI, 64291 Darmstadt, Germany
19
Frankfurt Institute for Advanced Studies (FIAS), 60438 Frankfurt am Main, Germany
20
Department of Physics, University of Surrey, Guildford, GU2 7XH, UK
21
Physics Department, University of Lund, Box-118, 22100 Lund, Sweden
22
II. Physikalisches Institut, Universit¨at Gießen, 35392 Gießen, Germany
23
Department of Nuclear Physics, Australian National University, Canberra ACT 0200,
Australia
24
Institut f¨ur Kernchemie, Universit¨at Mainz, 55128 Mainz, Germany
25
Helmholtz Institute Mainz, 55099 Mainz, Germany
26
Facultad de F´ısicas, Universidad Complutense, 28040 Madrid, Spain
27
Department of Physics, University of Jyv¨askyl¨a, 40014 Jyv¨askyl¨a, Finland
28
Helsinki Institute of Physics, University of Helsinki, 00014 Helsinki, Finland
29
Goethe-Universit¨at Frankfurt, 60438 Frankfurt, Germany
30
Fakult¨at f¨ur Physik, Ludwig-Maximilians-Universit¨at M¨unchen, 85748 Garching,
Germany
31
NSCL, Michigan State University, East Lansing, Michigan 48824, USA
32
Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China
33
Department of Physics, University of York, York YO10 5DD, UK
34
Department of Fundamental Physics, Chalmers University of Technology,
412 96 G¨oteborg, Sweden
35
Kernfysisch Versneller Institute (KVI), University of Groningen, 9747 AA Groningen,
The Netherlands
36
Nuclear Physics Group, STFC Daresbury Laboratory, Daresbury, Warrington, WA4 4AD,
UK
37
School of Physics and Nuclear Energy Engineering, Beihang University, 100191 Beijing,
PR China
38
Faculty of Physics, University of Warsaw, 00-681 Warszawa, Poland
39
Institut f¨ur Kernphysik, Universit¨at zu K¨oln, 50937 K¨oln, Germany
40
Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
41
Instituto de F´ısica Corpuscular, CSIC-Uni. Valencia, 46071 Valencia, Spain
42
Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA
43
University of California, Lawrence Livermore National Laboratory, Livermore, CA 94550,
USA
44
Department of Atomic Physics, Stockholm University, AlbaNova, 10691 Stockholm,
Sweden
45
Weizmann Institute of Science, Rehovot 76100, Israel
46
Institute of Physics, Ernst-Moritz-Arndt-University Greifswald, 17487 Greifswald,
Germany
47
Friedrich-Schiller-Universit¨at Jena, 07737 Jena, Germany
48
Helmholtz Institute Jena, 07743 Jena, Gemany
49
Department of Physics, Saitama University, Saitama 338-8570, Japan
50
Institut de Physique Nucl´eaire (IPN), 91406 Orsay, France
51
Institut f¨ur Kern- und Teilchenphysik, Technische Universit¨at Dresden, 01069 Dresden,
Germany
Received 13 January 2012 / Received in final form 15 March 2012
Published online 11 May 2012
Abstract. We propose to install a storage ring at an ISOL-type radioac-
tive beam facility for the first time. Specifically, we intend to setup the
heavy-ion, low-energy ring TSR at the HIE-ISOLDE facility in CERN,
Geneva. Such a facility will provide a capability for experiments with
stored secondary beams that is unique in the world. The envisaged
Storage Ring at HIE-ISOLDE 3
physics programme is rich and varied, spanning from investigations of
nuclear ground-state properties and reaction studies of astrophysical
relevance, to investigations with highly-charged ions and pure isomeric
beams. The TSR might also be employed for removal of isobaric con-
taminants from stored ion beams and for systematic studies within
the neutrino beam programme. In addition to experiments performed
using beams recirculating within the ring, cooled beams can also be
extracted and exploited by external spectrometers for high-precision
measurements. The existing TSR, which is presently in operation at
the Max-Planck Institute for Nuclear Physics in Heidelberg, is well-
suited and can be employed for this purpose. The physics cases as well
as technical details of the existing ring facility and of the beam and in-
frastructure requirements at HIE-ISOLDE are discussed in the present
technical design report.
1 Introduction
Nuclear physics experiments with stored exotic nuclei have demonstrated their enor-
mous scientific potential in recent years [1,2]. Presently there are two heavy-ion
storage ring facilities worldwide performing such experiments, namely the ESR in
Darmstadt and the CSRe in Lanzhou [3]. However, these facilities are specialized
for experiments at relativistic energies, but a broad range of new experiments would
become possible with the availability of stored secondary beams at lower energies
(0.5–10 MeV/u). Although slowing down of stored beams can be done at the exist-
ing storage rings, it is a time consuming and inefficient process that has so far been
limited to stable nuclides.
An important distinctive feature of this proposal is that the ion beams will be
produced by the Isotope Separation On-Line (ISOL) method, whereas both of the
existing storage ring facilities are based on the in-flight production of secondary beams
at high energies (∼1GeV/u)[3]. The complementary ISOL method employed at
ISOLDE is superior in terms of the beam intensity for a large number of elements
and the beam quality. Moreover, the existing and planned post-acceleration schemes
can deliver high-quality ISOL beams right at the required energies, which circumvents
the long slowing down times required for the relativistic ion beams.
We propose to install a low-energy heavy-ion storage ring at an ISOL facility for
the first time. We will cool and store post-accelerated high-intensity beams avail-
able from HIE-ISOLDE at CERN using the existing ring TSR, which is presently
in operation at the Max-Planck Institute for Nuclear Physics in Heidelberg (MPIK)
[4,5]. This will open up an extremely rich scientific programme in nuclear physics,
nuclear astrophysics and atomic physics. We emphasize that most of the discussed
experiments can only be done with the proposed facility.
This Technical Design Report describes the physics motivation (Sect. 2), beam
requirements for the HIE-ISOLDE facility (Sect. 3), technical specifications of the
TSR (Sect. 4), as well as the required infrastructure and supplies (Sect. 5).
2 Physics motivation
2.1 Introduction: Beam properties in the TSR
The use of the Test Storage Ring coupled to the HIE-ISOLDE post-accelerator offers
a number of unique opportunities for research in nuclear and atomic physics. The
topics are explored in the following chapters, where some concrete examples are also
4 The European Physical Journal Special Topics
Table 1. Parameters of beams circulating in the TSR. See text for details.
Ion Nuclear Energy Cooling Beam H
2
target Beam Eff. target
lifetime (MeV/u) time lifetime in (atoms/cm
2
) lifetime thickness
residual gas in target (µg/cm
2
)
7
Be 3
+
(53 d) 10 2.3 s 370 s
18
F9
+
100 m 10 0.7 s 280 s 1 × 10
14
236 s 31000
26m
Al 13
+
6.3 s 10 0.5 s 137 s 5 × 10
14
23 s 4200
52
Ca 20
+
4.6 s 10 0.4 s 58 s 5 × 10
14
9.6 s 3000
70
Ni 28
+
6.0 s 10 0.25 s 30 s 2 × 10
14
12 s 1600
70
Ni 25
+
6.0 s 10 0.3 s 26 s 2 × 10
13
2.1 s 60
132
Sn 30
+
40 s 4 0.4 s 1.5 s 1 × 10
12
1.4 s 1.2
132
Sn 45
+
40 s 4 0.2 s 1.4 s 5 × 10
12
1.6 s 7
132
Sn 39
+
40 s 10 0.25 s 7.4 s 2 × 10
12
3.6 s 9.5
132
Sn 45
+
40 s 10 0.2 s 10 s 5 × 10
13
1.3 s 90
186
Pb 46
+
4.8 s 10 0.25 s 4 s 2 × 10
12
1.5 s 4
186
Pb 64
+
4.8 s 10 0.13 s 5 s 1 × 10
13
1.7 s 20
discussed. In this context it is useful to briefly review the general features of the
different ways in which experiments are foreseen to be performed at the TSR. The
short illustration that follows is based on the extended descriptions given in the
technical sections – in particular Sect. 3 (the post-accelerator) and 4 (the storage
ring).
The way to achieve an efficient transfer of the ion beam into the TSR at Hei-
delberg is by occupying the available phase space through a “multi-turn” injection
(see Chapt. 4.5). This operation is fast (≈50 µs using 40 turns at a beam energy of
10 MeV/nucleon), however it has to be followed by a cooling time during which the
beam is reduced in energy spread and size, from a diameter of a few centimeters to
about 1 mm. This is achieved with electron cooling, described in Chapt. 4.6. Cooling
times may vary between about 0.1 s and about one second. When cooling is complete,
a measurement can take place in the TSR, until the following injection. Alternatively,
several injection-cooling cycles can follow each other increasing the particle current,
before performing the measurement. With the present power supplies, the frequency
of injections is limited to 5 Hz, however a lower frequency needs to be used to allow
time for the measurement. Notice that the new injection does not affect the beam
already circulating in the TSR: the intensity simply adds up (the maximum current
which can be stored is about 1 mA).
The timing properties of the ion beams post-accelerated in HIE-ISOLDE are de-
termined by the operation modes of REXTRAP and REXEBIS. Currently at the
ISOLDE accelerator REX, beam particles are bunched in short bursts (≈100 µs) at
repetition rates of 3 Hz to 50 Hz. The extraction time is already compatible with the
multi-turn injection into the TSR, and by accumulating the ions for a longer time in
REXTRAP the repetition can be lowered to suit the operation of TSR and thereby
ensure an optimal use of the HIE-ISOLDE beams.
The cooling times of various beams are reported in Table 1. The calculations are
explained in detail in Chapt. 4.6.2. Table 1 also shows the expected lifetime of beams
in the TSR, as determined by the interaction with the residual gas (at a pressure
of 2 × 10
−10
mbar) and with a H
2
gas target (a gas-jet target or similar, as it could
be used for reaction measurements) of a given thickness. The lifetimes are calculated
using the prescriptions of Nikolaev et al. [6] for electron capture cross sections, and
Dmitriev et al. [7] for electron stripping (further details are given in Chapt. 4.8). The
target thickness is chosen in order to ensure a sufficiently long lifetime, and reflects
Storage Ring at HIE-ISOLDE 5
53.29(7) d
Be
7
4
0
3/2
-
stable
73 fs
100 %
0
89.48 %
10.52 %
EC
Q = 861.815 (18)
Li
7
3
3/2
-
1/2
-
477.612
Fig. 1. Known decay scheme of neutral
7
Be atoms [8].
the characteristics of gas targets presently used in storage rings. It is also important
to mention that, owing to a large momentum acceptance of the TSR of ±3% [5], a
simultaneous storage of the beam in several atomic charge-states is feasible (for more
details see Sect. 4.4). In this case the losses of the stored beam due to atomic electron
stripping/pick-up reactions can be significantly reduced.
For the calculation of the total current intensity in the TSR, one has to consider the
shortest one between the lifetimes quoted in Table 1.Ifτ is this shortest lifetime and
i is the intensity of the post-accelerated beam in HIE-ISOLDE, the total intensity
of the beam circulating in the TSR is given by I = ifτ, where is the injection
efficiency and f is the revolution frequency (about 790 kHz at 10 MeV/nucleon). One
can see that an increase in intensity of several orders of magnitude can be achieved.
For experiments using an internal gas target, the intensity increase should counter
the much lower target thickness of the gas jet when compared to target foils used in
conventional setups. This can be evaluated by defining the “effective target thickness”
shown in the last column of Table 1, which is calculated by multiplying the thickness
of the gas target by the increase in beam intensity fτ (the injection efficiency is here
assumed to be 100% for simplicity). To attain a usable effective target thickness,
energies of 10 MeV/nucleon and high charge states are desirable; the latter help both
by allowing a shorter cooling time and smaller cross section for electron capture and
stripping.
Experiments can also be performed with a beam extracted from the TSR. The
details of this operation are described in Chapt. 4.10. The extracted beam is es-
sentially DC, which can be of great advantage in experiments for which the high
instantaneous rate of HIE-ISOLDE beams is a problem. In addition, the optical and
purity characteristics of the extracted beam can be of much higher quality than the
direct HIE-ISOLDE beam, thanks to mass-selective acceleration (Chapt. 4.9.1)and
cooling in the TSR. Possibilities of measurements with extracted beams are further
elaborated in Chapt. 2.7.4.
2.2 Half-lives of
7
Be in different atomic charge states
The decay scheme of neutral
7
Be atoms is shown in Fig. 1. Neutral
7
Be atoms are
radioactive and decay with the half-life of about 53 d [8] to stable
7
Li atoms via the
only energetically allowed decay channel, namely the orbital electron capture decay
(EC):
7
Be(e
−
,ν)
7
Li .
![Fig. 8. Hyperfine-split DR resonances of 45Sc18+ (I = 7/2, µI = 4.7565) [157] of (1s2 2p3/210d3/2)J=3 doubly excited states. The separation of the resonance states that are just 6 meV apart could be achieved exploiting the unique capabilities of the TSR highresolution electron target. Please note, that the two F -states are about equally populated.](/figures/fig-8-hyperfine-split-dr-resonances-of-45sc18-i-7-2-ui-4-1vcok76p.webp)