- Email: [email protected]
Physics with SPIRAL and SPIRAL 2 status of the EURISOL project
Nuclear Physics A734 (2004) 645-653 www.elsevier.comllocateinpe
Physics with SPIRAL and SPIRAL 2 Status of the EURISOL Project M. Lewitowicz”
‘Grand Acc61Brateur National d’Ions Lourds B.P. 55027, 14076 Caen Cedex, France Examples of recent results obtained with SPIRAL beams on the properties of nuclei in the vicinity of drip-lines and/or magic numbers are presented. The future plans of the GANIL/SPIRAL facility related to the SPIRAL 2 project are described. The curent status of EURISOL, the european ultimate ISOL-based radioactive beam facility, is shortly presented. 1. PHYSICS 1.1.
WITH
SPIRAL
AND
SPIRAL
2
Introduction
The nuclear structure, well established for nuclei close to the valley of stability, is expected to evolve significantly in the presence of important excess of neutrons or protons. Nuclei in the vicinity of the drip lines exhibit particularly important changes in the intrinsic structure related to the very low binding energy and the strong influence of the continuum states. In order to obtain the most complete information on these effects a use of radioactive beams in a wide range of isospin and energy is necessary. High energy beams produced by in-flight fragmentation and post-accelerated ISOL beams proved to be complementary with respect to their intensity, isotopic purity and optical quality. Both techniques currently in use at the GANIL/SPIRAL facility offer unique possibilities to make experiments with light radioactive beams (A<80) in the energy range from 30 keV/nucleon to about 80 MeV/nucleon. The successful experimental program of study of nuclei far from stability going on since about 15 years at GANIL using radioactive beams produced in-flight was extended recently towards new possibilities offered by high-quality, low energy radioactive beams available at the SPIRAL facility. In the present paper only one example of the studies of nuclei far from stability with SPIRAL beams is described in detail. Many other new results obtained at GANIL were presented in several contributions to this conference (see figure 1). 1.2.
The
SPIRAL
facility
The SPIRAL facility combines the ISOL production method, a universal and fast graphite target, an ECR source for ionization of radioactive atoms with high power (today 1.7 kW, up to 6 kW in the close future) heavy ion stable beams from GANIL cyclotrons. 0375-9474/$ - see front matter 0 2004 Elsevier B.V. All rights reserved dol: 10.1016/j.nuc1physa.2004.01.1I8
646
M. Lewitowicz/Nuclear
Physics A734 (2004) 645-653
~~~*~~~~~ N-
D. Guillemaud-Mueller
et al.
Figure 1. Recent highlights of studies of exotic nuclei at GANIL. The names of speakers presenting a given topic at the conference are also indicated.
The radioactive beams are accelerated and separated in the newly constructed CIME cyclotron. A construction of SPIRAL was accomplished in 2001 and detailed tests performed with stable and radioactive beams have shown an excellent overall acceleration efficiency of the accelerating system (from the exit of the ion source to the secondary target) ranging from about 20 to 35%. During the first year and a half of operation SPIRAL was be able to deliver radioactive beams of noble gases (He, Ne, Ar and Kr) with an intensity of 10410’ particles per second in the energy range from about 3 to 15 AMeV (see table 1). The high purity (in all cases better than 99%) of the radioactive beams was obtained combining a chemical selectivity of the target-ion source system (not heated transfer tube) and the high mass resolving power of the CIME cyclotron (up to 10000). As intensities of low energy radioactive beams are usually four or five orders of magnitude lower than typical intensities of stable beams the RNB experiments require detection devices of a very high efficiency. Two of them, namely a 4II y-array called EXOGAM and a high acceptance, variable mode magnetic spectrometers called VAMOS became operational recently at GANIL. These two spectrometers in combinations with charged particle detectors like MUST, TIARA and DIAMON are ideal tools for study nuclear structure as well as reaction mechanism in reactions with low energy stable and radioactive beams. These devices were already used in successful experiments on elastic and inelastic scattering of *He, on sub-barrier Coulomb excitation of 74,76Kr beams, fusion-evaporation reactions with and 76Kr beams and others.
M. Lewitowicz/Nuclear
Figure 2. Layout of the GANIL/SPIRAL
Physics A734 (2004) 645-653
647
facility.
1.3. First experiments with SPIRAL beams The first SPIRAL experiment was dedicated to a measurement of the excited states of lgNa with the resonant elastic scattering method [l]. Other experiments deal with the following topics: l
Search for the 4n resonances with the ‘He beam;
l
Structure of halo nuclei in the elastic, inelastic scattering and transfer reactions with 8He;
l
Sub-barrier fusion with halo nuclei studied via y-ray spectroscopy with the 6v8He beams;
l
Study of K-isomers in the PO isotopes in fusion- evaporation reactions and in-beam y-ray spectroscopy with the 8He beam;
l
Structure of very neutron deficient A=130 nuclei in fusion-evaporation reactions and in-beam y-ray spectroscopy with the 76Kr beam;
l
Low-energy Coulomb excitation of light Kr isotopes.
In the following we will concentrate on the last item. On the proton rich side of the chart of nuclei, an observation of the O+ isomeric states (see upper part of figure 3) through the y-ray and conversion electron spectroscopy applied to the fast fragmentation products gives an opportunity to follow the shape evolution in the 72-74Kr region [2]. A
M. Lewitowicz/Nuclear
648
Physics d 734 (2004) 645-653
Table 1 First radioactive nuclear beams of the SPIRAL facility. Ion Energy Intensity A MeV PPS ‘Hei+ ‘He’+ *He2+ 16Ne4+ 76~~11+ 74Kr11+
5 3.4 15.4 7 4.3 4.3
3x107
5x10* 1.3x104 2x106 5x105
1x104
simple analysis of these results in the framework of the two level mixing model suggests an oblate-prolate shape coexistence with equal amplitudes in 74Kr. Similarly, the ground state of the N=Z nucleus 72Kr was deduced to have almost pure oblate configuration. Further insight on the shape evolution in these nuclei can be obtained by means of the low energy Coulomb excitation experiments with SPIRAL beams. Two experiments of this kind were performed with 76Kr and recently with 74Kr in order to measure the transition probabilities B(E2) and the static quadrupole moments. The first of these quantities allows to deduce an absolute value of deformation, the second its sign. The use of the Coulomb excitation reactions gives an opportunity to excite both yrast and non-yrast states in the projectile. The experiments were performed at the beam energies of 4.3 A MeV on titanium and lead targets. The experimental set-up consisted of the EXOGAM gamma array (4 to 8 clover detectors) and a silicon-strip detector in order to detect an angle and energy of the projectile-like or target-like particles. A preliminary analysis of the 76Kr data shows, for the first time experimentally, that the ground-state band of this nucleus is prolate. At the same time the second 2+ state seems to have an oblate deformation [3]. A n excellent quality data, as shown in figure 3, were obtained recently for the Coulomb excitation of 74Kr. Due to the high selectivity of the y-raycharged particle coincidences no pits corresponding to the P-7 decay of the radioactive beam are present in the measured spectrum. The analysis of the data is in progress [3]. 1.4.
The
SPIRAL
2 facility
It is planned that in few years from now a relatively limited range of ions produced by the SPIRAL facility will be extended to heavier neutron-rich nuclei produced in a low energy fission of uranium in the proposed SPIRAL 2 facility [4]. A full description of the nuclear physics topics and interdisciplinary applications which might be covered with the SPIRAL 2 beams is beyond the scope of this contribution, but one can mention that both high-intensity stable and fission-fragment radioactive beams can be used to cover very broad range of nuclei very far from stability (Fig. 5). A use of these high-intensity beams at the GANIL low-energy ISOL facility or their acceleration to a few tens of MeV/nucleon opens new possibilities in nuclear structure physics, nuclear astrophysics, reaction dynamics studies as well as in atomic physics,
A4. LewitowiczlNuclear
Ph,vsics
A734
4+ tl \o
(2004)
645653
;% # E
649
0+770
2+
671
o+
2+
0+
2
EO
0+
h
Energy (keV) Figure 3. Upper part: partial decay scheme of the light even krypton isotopes indicating position of the low lying second O+ state. Lower part: preliminary, on-line gamma-ray spectrum measured with the EXOGAM array for the Coulomb excitation of the 74Kr beam produced at SPIRAL.
condensed matter studies, radio-biology and radiochemistry (see [4]). A layout of SPIRAL 2 is presented in figure 4. A new superconducting linear driver (LINAG) will deliver a high intensity, 40 MeV deuteron beam as well as a variety of heavy-ion beams with mass over charge ratio equals to 3 and energy up to 14.5 AMeV. Using a carbon converter and the 5 mA deuteron beam, a neutron-induced fission rate is expected be 1.3 x 1013 fissions/s with a low density UC, target, and up 5.3 x 1013 fissions/s for high-density UC,. The expected intensities of RNBs after acceleration should reach, for example, 10’ pps for 13’Sn and lOlo pps for “Kr . Besides the method which uses a carbon converter, a direct irradiation of the UC, with beams of d, 3p4He 617Li or “C can be applied if a higher excitation energy leads to higher production rate for a nucleus of interest. The neutron-rich fission products could be complemented by nuclei near the proton drip line provided by fusion-evaporation reactions. For example, a production of up to
650
M. Lewitowicz/Nuclear
Physics A734 (2004) 645-653
RFQ - 0.75A MeV
Figure 4. Schematic layout of the proposed SPIRAL 2 facility.
8 x lo4 atoms of “Zr per second using a 200 PA 24Mg8+ beam on a 58Ni target should be possible. The extracted ISOL-type RNBs will be subsequently accelerated to energies of up to about 7-8 AMeV in the existing CIME cyclotron. Regions of the chart of nuclei which will be accessible with both radioactive and stable SPIRAL 2 beams are shown in figure 5. One of the important feature of the future GANIL/SPIRAL/SPIRAL 2 facility will be a possibility to deliver up to five stable or radioactive beams simultaneously. For example, let’s assume that using the LINAG accelerator and the adequate uranium target one produces high intensity radioactive beams of fission fragments. After ionization a beam of the given mass Ai can be used in the very low energy experimental area. At the same time mass separator will deliver another beam of mass As for the further acceleration in the CIME cyclotron. This beam, thanks to the dedicated beam line from CIME to the Gl and G2 caves, can be used for experiments with EXOGAM and VAMOS. Simultaneously, the standard GANIL beams can be accelerated and used in the IRRSUD facility (stable beams at about 1 AMeV), at the SME beam line (stable beams at 8-10 AMeV) and in the existing experimental area (50-100 AMeV stable or radioactive beams produced in-flight). The full cost of the SPIRAL 2 facility is estimated to 80 MEuros. The detailed design study of the project will be complited next year. One might expect a decision of the construction of the facility to be taken in 2004, allowing a first beam to be delivered in 2008. Numerous international collaborations are currently under elaboration in order to construct and operate the facility on the fully European basis.
M. Lewitowicz/Nuclear
651
Physics A734 (2004) 645-653
' %Transfermiums
5 +
2
28
3.Fission
r,
2. Fusion reaction with n-rich beams
r,
l.Fission
In-flight(Z=106,108)
products(with
converter)
products(withoutconverter)
Figure 5. Regions of the chart of nuclei covered by beams of the SPIRAL 2 facility.
2. STATUS
OF THE EURISOL
PROJECT
EURISOL [5] is the research and technical development project in nuclear physics aimed at completing a preliminary design study of the next-generation European ISOL radioactive nuclear beam facility. The resulting facility is intended to extend and amplify, beyond 2010, the exciting work presently being carried out using the first-generation RNB facilities like SPIRAL or REX ISOLDE in various scientific disciplines including nuclear physics, nuclear astrophysics and fundamental interactions. This 3-year study is going to thoroughly investigate the scientific and technical challenges posed by such a facility, identify the R and D required before a full engineering design can be undertaken, and establish a cost-estimate of capital investment and running costs. Possible synergies with other European installations and projects are also considered. The collaborating institutions are : Universit Catholique de Louvain (UCL), Louvain-laNeuve, Belgium (Project Coordinator: Jean Vervier); Grand Accelerateu National d’Ions Lourds (GANIL), Caen, France (Coordinating Institute); Chalmers University of Technology (CUT), Goteborg, Sweden; Katholieke Universiteit Leuven (KULeuven), Belgium; Gesellschaft fur Schwerionenforschung (GSI), Darmstadt, Germany; Istituto Nazionale di Fisica Nucleare (INFN), Roma, Italy; Institut de Physique Nuclaire Orsay (IPNO), Orsay, and CEA/DAPNIA, Saclay, France; ISOLDE, CERN, Genve, Switzerland, and University of Mainz, Germany; Accelerator Laboratory, University of Jyviiskyla, (JYFL) Finland; Rutherford Appleton Laboratory (RAL), Didcot, United Kingdom. The project is divided into following tasks:
M. Lewitowicz/Nuclear
652
PROVISIONNAL
Physm A734 (2004) 645-653
FACILITY
LAYOUT
Experimental
II
areas
Low energy (470 keV/u) Astrophysics ((3.2 Me V/u)
Chqe 4ectim
l?me-oC-tlight sepluator
Medium energy (~18 Mel//u) High energy (
Figure 6. Schematic layout of the EURISOL facility.
l
Identify Key Experiments - types of RNB needed, energy, intensity, expected crosssections of exotic nuclei from various mechanisms (spallation, fragmentation, fission...).
l
Investigate Driver Accelerator options in detail. Study possible acceleration of protons, deuterons (for producing fast neutrons), light ions, heavy ions. Look at energy range and intensities from cyclotrons, linacs, etc., and their superconducting variants.
l
Elaborate a conceptual layout of the Target/Ion-Source Assembly, able to withstand high beam power and to produce radioactive ions with high efficiency. Investigate fission, spallation and fragmentation targets, laser ion sources, ion-guide ISOL (IGISOL) systems, as well as radiation protection and remote handling. Identify key technologies and explore the R and D needed.
l
Investigate the various options of Mass-Selection System for the ions produced in the target/ion-source assembly, and the type of Postaccelerator to be used. Consider RFQ injectors, linacs (possibly superconducting), and cyclotrons - which can also act as a mass selector. Look into storage rings/recirculators.
M. Lewitowicz/Nucleau
l
l
Physics
A734
(2004)
645-653
653
Identify the main scientific Instrumentation to be installed. Look into high detection efficiency, high granularity, good mass/energy resolution and good timing resolution. Establish a Cost Estimate for the planned facility. Include buildings, utilities, the EURISOL accelerators, instrumentation and running costs.
The current status of the project, summarized in the draft reports of the task groups [5], leads to the schematic layout of the future facility presented in figure 6. The final report on the EURISOL project is expected in the end of 2003. 3. CONCLUSIONS The GANIL facility offers unique possibilities to study nuclei far from stability using both fragmentation-like (A
Nouvelles du GANIL, Hors Sdrie, GANIL, February 2002. E. Bouchez et al., Phys. Rev. Lett. 90 (2003) 082502. E. Bouchez PhD thesis 2003, Strasbourg University, to be published. SPIRAL II Web page, www.ganil.fr. EURISOL Web page, www.ganil.fr/eurisol.
Physics with SPIRAL and SPIRAL 2 Status of the EURISOL Project M. Lewitowicz”
‘Grand Acc61Brateur National d’Ions Lourds B.P. 55027, 14076 Caen Cedex, France Examples of recent results obtained with SPIRAL beams on the properties of nuclei in the vicinity of drip-lines and/or magic numbers are presented. The future plans of the GANIL/SPIRAL facility related to the SPIRAL 2 project are described. The curent status of EURISOL, the european ultimate ISOL-based radioactive beam facility, is shortly presented. 1. PHYSICS 1.1.
WITH
SPIRAL
AND
SPIRAL
2
Introduction
The nuclear structure, well established for nuclei close to the valley of stability, is expected to evolve significantly in the presence of important excess of neutrons or protons. Nuclei in the vicinity of the drip lines exhibit particularly important changes in the intrinsic structure related to the very low binding energy and the strong influence of the continuum states. In order to obtain the most complete information on these effects a use of radioactive beams in a wide range of isospin and energy is necessary. High energy beams produced by in-flight fragmentation and post-accelerated ISOL beams proved to be complementary with respect to their intensity, isotopic purity and optical quality. Both techniques currently in use at the GANIL/SPIRAL facility offer unique possibilities to make experiments with light radioactive beams (A<80) in the energy range from 30 keV/nucleon to about 80 MeV/nucleon. The successful experimental program of study of nuclei far from stability going on since about 15 years at GANIL using radioactive beams produced in-flight was extended recently towards new possibilities offered by high-quality, low energy radioactive beams available at the SPIRAL facility. In the present paper only one example of the studies of nuclei far from stability with SPIRAL beams is described in detail. Many other new results obtained at GANIL were presented in several contributions to this conference (see figure 1). 1.2.
The
SPIRAL
facility
The SPIRAL facility combines the ISOL production method, a universal and fast graphite target, an ECR source for ionization of radioactive atoms with high power (today 1.7 kW, up to 6 kW in the close future) heavy ion stable beams from GANIL cyclotrons. 0375-9474/$ - see front matter 0 2004 Elsevier B.V. All rights reserved dol: 10.1016/j.nuc1physa.2004.01.1I8
646
M. Lewitowicz/Nuclear
Physics A734 (2004) 645-653
~~~*~~~~~ N-
D. Guillemaud-Mueller
et al.
Figure 1. Recent highlights of studies of exotic nuclei at GANIL. The names of speakers presenting a given topic at the conference are also indicated.
The radioactive beams are accelerated and separated in the newly constructed CIME cyclotron. A construction of SPIRAL was accomplished in 2001 and detailed tests performed with stable and radioactive beams have shown an excellent overall acceleration efficiency of the accelerating system (from the exit of the ion source to the secondary target) ranging from about 20 to 35%. During the first year and a half of operation SPIRAL was be able to deliver radioactive beams of noble gases (He, Ne, Ar and Kr) with an intensity of 10410’ particles per second in the energy range from about 3 to 15 AMeV (see table 1). The high purity (in all cases better than 99%) of the radioactive beams was obtained combining a chemical selectivity of the target-ion source system (not heated transfer tube) and the high mass resolving power of the CIME cyclotron (up to 10000). As intensities of low energy radioactive beams are usually four or five orders of magnitude lower than typical intensities of stable beams the RNB experiments require detection devices of a very high efficiency. Two of them, namely a 4II y-array called EXOGAM and a high acceptance, variable mode magnetic spectrometers called VAMOS became operational recently at GANIL. These two spectrometers in combinations with charged particle detectors like MUST, TIARA and DIAMON are ideal tools for study nuclear structure as well as reaction mechanism in reactions with low energy stable and radioactive beams. These devices were already used in successful experiments on elastic and inelastic scattering of *He, on sub-barrier Coulomb excitation of 74,76Kr beams, fusion-evaporation reactions with and 76Kr beams and others.
M. Lewitowicz/Nuclear
Figure 2. Layout of the GANIL/SPIRAL
Physics A734 (2004) 645-653
647
facility.
1.3. First experiments with SPIRAL beams The first SPIRAL experiment was dedicated to a measurement of the excited states of lgNa with the resonant elastic scattering method [l]. Other experiments deal with the following topics: l
Search for the 4n resonances with the ‘He beam;
l
Structure of halo nuclei in the elastic, inelastic scattering and transfer reactions with 8He;
l
Sub-barrier fusion with halo nuclei studied via y-ray spectroscopy with the 6v8He beams;
l
Study of K-isomers in the PO isotopes in fusion- evaporation reactions and in-beam y-ray spectroscopy with the 8He beam;
l
Structure of very neutron deficient A=130 nuclei in fusion-evaporation reactions and in-beam y-ray spectroscopy with the 76Kr beam;
l
Low-energy Coulomb excitation of light Kr isotopes.
In the following we will concentrate on the last item. On the proton rich side of the chart of nuclei, an observation of the O+ isomeric states (see upper part of figure 3) through the y-ray and conversion electron spectroscopy applied to the fast fragmentation products gives an opportunity to follow the shape evolution in the 72-74Kr region [2]. A
M. Lewitowicz/Nuclear
648
Physics d 734 (2004) 645-653
Table 1 First radioactive nuclear beams of the SPIRAL facility. Ion Energy Intensity A MeV PPS ‘Hei+ ‘He’+ *He2+ 16Ne4+ 76~~11+ 74Kr11+
5 3.4 15.4 7 4.3 4.3
3x107
5x10* 1.3x104 2x106 5x105
1x104
simple analysis of these results in the framework of the two level mixing model suggests an oblate-prolate shape coexistence with equal amplitudes in 74Kr. Similarly, the ground state of the N=Z nucleus 72Kr was deduced to have almost pure oblate configuration. Further insight on the shape evolution in these nuclei can be obtained by means of the low energy Coulomb excitation experiments with SPIRAL beams. Two experiments of this kind were performed with 76Kr and recently with 74Kr in order to measure the transition probabilities B(E2) and the static quadrupole moments. The first of these quantities allows to deduce an absolute value of deformation, the second its sign. The use of the Coulomb excitation reactions gives an opportunity to excite both yrast and non-yrast states in the projectile. The experiments were performed at the beam energies of 4.3 A MeV on titanium and lead targets. The experimental set-up consisted of the EXOGAM gamma array (4 to 8 clover detectors) and a silicon-strip detector in order to detect an angle and energy of the projectile-like or target-like particles. A preliminary analysis of the 76Kr data shows, for the first time experimentally, that the ground-state band of this nucleus is prolate. At the same time the second 2+ state seems to have an oblate deformation [3]. A n excellent quality data, as shown in figure 3, were obtained recently for the Coulomb excitation of 74Kr. Due to the high selectivity of the y-raycharged particle coincidences no pits corresponding to the P-7 decay of the radioactive beam are present in the measured spectrum. The analysis of the data is in progress [3]. 1.4.
The
SPIRAL
2 facility
It is planned that in few years from now a relatively limited range of ions produced by the SPIRAL facility will be extended to heavier neutron-rich nuclei produced in a low energy fission of uranium in the proposed SPIRAL 2 facility [4]. A full description of the nuclear physics topics and interdisciplinary applications which might be covered with the SPIRAL 2 beams is beyond the scope of this contribution, but one can mention that both high-intensity stable and fission-fragment radioactive beams can be used to cover very broad range of nuclei very far from stability (Fig. 5). A use of these high-intensity beams at the GANIL low-energy ISOL facility or their acceleration to a few tens of MeV/nucleon opens new possibilities in nuclear structure physics, nuclear astrophysics, reaction dynamics studies as well as in atomic physics,
A4. LewitowiczlNuclear
Ph,vsics
A734
4+ tl \o
(2004)
645653
;% # E
649
0+770
2+
671
o+
2+
0+
2
EO
0+
h
Energy (keV) Figure 3. Upper part: partial decay scheme of the light even krypton isotopes indicating position of the low lying second O+ state. Lower part: preliminary, on-line gamma-ray spectrum measured with the EXOGAM array for the Coulomb excitation of the 74Kr beam produced at SPIRAL.
condensed matter studies, radio-biology and radiochemistry (see [4]). A layout of SPIRAL 2 is presented in figure 4. A new superconducting linear driver (LINAG) will deliver a high intensity, 40 MeV deuteron beam as well as a variety of heavy-ion beams with mass over charge ratio equals to 3 and energy up to 14.5 AMeV. Using a carbon converter and the 5 mA deuteron beam, a neutron-induced fission rate is expected be 1.3 x 1013 fissions/s with a low density UC, target, and up 5.3 x 1013 fissions/s for high-density UC,. The expected intensities of RNBs after acceleration should reach, for example, 10’ pps for 13’Sn and lOlo pps for “Kr . Besides the method which uses a carbon converter, a direct irradiation of the UC, with beams of d, 3p4He 617Li or “C can be applied if a higher excitation energy leads to higher production rate for a nucleus of interest. The neutron-rich fission products could be complemented by nuclei near the proton drip line provided by fusion-evaporation reactions. For example, a production of up to
650
M. Lewitowicz/Nuclear
Physics A734 (2004) 645-653
RFQ - 0.75A MeV
Figure 4. Schematic layout of the proposed SPIRAL 2 facility.
8 x lo4 atoms of “Zr per second using a 200 PA 24Mg8+ beam on a 58Ni target should be possible. The extracted ISOL-type RNBs will be subsequently accelerated to energies of up to about 7-8 AMeV in the existing CIME cyclotron. Regions of the chart of nuclei which will be accessible with both radioactive and stable SPIRAL 2 beams are shown in figure 5. One of the important feature of the future GANIL/SPIRAL/SPIRAL 2 facility will be a possibility to deliver up to five stable or radioactive beams simultaneously. For example, let’s assume that using the LINAG accelerator and the adequate uranium target one produces high intensity radioactive beams of fission fragments. After ionization a beam of the given mass Ai can be used in the very low energy experimental area. At the same time mass separator will deliver another beam of mass As for the further acceleration in the CIME cyclotron. This beam, thanks to the dedicated beam line from CIME to the Gl and G2 caves, can be used for experiments with EXOGAM and VAMOS. Simultaneously, the standard GANIL beams can be accelerated and used in the IRRSUD facility (stable beams at about 1 AMeV), at the SME beam line (stable beams at 8-10 AMeV) and in the existing experimental area (50-100 AMeV stable or radioactive beams produced in-flight). The full cost of the SPIRAL 2 facility is estimated to 80 MEuros. The detailed design study of the project will be complited next year. One might expect a decision of the construction of the facility to be taken in 2004, allowing a first beam to be delivered in 2008. Numerous international collaborations are currently under elaboration in order to construct and operate the facility on the fully European basis.
M. Lewitowicz/Nuclear
651
Physics A734 (2004) 645-653
' %Transfermiums
5 +
2
28
3.Fission
r,
2. Fusion reaction with n-rich beams
r,
l.Fission
In-flight(Z=106,108)
products(with
converter)
products(withoutconverter)
Figure 5. Regions of the chart of nuclei covered by beams of the SPIRAL 2 facility.
2. STATUS
OF THE EURISOL
PROJECT
EURISOL [5] is the research and technical development project in nuclear physics aimed at completing a preliminary design study of the next-generation European ISOL radioactive nuclear beam facility. The resulting facility is intended to extend and amplify, beyond 2010, the exciting work presently being carried out using the first-generation RNB facilities like SPIRAL or REX ISOLDE in various scientific disciplines including nuclear physics, nuclear astrophysics and fundamental interactions. This 3-year study is going to thoroughly investigate the scientific and technical challenges posed by such a facility, identify the R and D required before a full engineering design can be undertaken, and establish a cost-estimate of capital investment and running costs. Possible synergies with other European installations and projects are also considered. The collaborating institutions are : Universit Catholique de Louvain (UCL), Louvain-laNeuve, Belgium (Project Coordinator: Jean Vervier); Grand Accelerateu National d’Ions Lourds (GANIL), Caen, France (Coordinating Institute); Chalmers University of Technology (CUT), Goteborg, Sweden; Katholieke Universiteit Leuven (KULeuven), Belgium; Gesellschaft fur Schwerionenforschung (GSI), Darmstadt, Germany; Istituto Nazionale di Fisica Nucleare (INFN), Roma, Italy; Institut de Physique Nuclaire Orsay (IPNO), Orsay, and CEA/DAPNIA, Saclay, France; ISOLDE, CERN, Genve, Switzerland, and University of Mainz, Germany; Accelerator Laboratory, University of Jyviiskyla, (JYFL) Finland; Rutherford Appleton Laboratory (RAL), Didcot, United Kingdom. The project is divided into following tasks:
M. Lewitowicz/Nuclear
652
PROVISIONNAL
Physm A734 (2004) 645-653
FACILITY
LAYOUT
Experimental
II
areas
Low energy (470 keV/u) Astrophysics ((3.2 Me V/u)
Chqe 4ectim
l?me-oC-tlight sepluator
Medium energy (~18 Mel//u) High energy (
Figure 6. Schematic layout of the EURISOL facility.
l
Identify Key Experiments - types of RNB needed, energy, intensity, expected crosssections of exotic nuclei from various mechanisms (spallation, fragmentation, fission...).
l
Investigate Driver Accelerator options in detail. Study possible acceleration of protons, deuterons (for producing fast neutrons), light ions, heavy ions. Look at energy range and intensities from cyclotrons, linacs, etc., and their superconducting variants.
l
Elaborate a conceptual layout of the Target/Ion-Source Assembly, able to withstand high beam power and to produce radioactive ions with high efficiency. Investigate fission, spallation and fragmentation targets, laser ion sources, ion-guide ISOL (IGISOL) systems, as well as radiation protection and remote handling. Identify key technologies and explore the R and D needed.
l
Investigate the various options of Mass-Selection System for the ions produced in the target/ion-source assembly, and the type of Postaccelerator to be used. Consider RFQ injectors, linacs (possibly superconducting), and cyclotrons - which can also act as a mass selector. Look into storage rings/recirculators.
M. Lewitowicz/Nucleau
l
l
Physics
A734
(2004)
645-653
653
Identify the main scientific Instrumentation to be installed. Look into high detection efficiency, high granularity, good mass/energy resolution and good timing resolution. Establish a Cost Estimate for the planned facility. Include buildings, utilities, the EURISOL accelerators, instrumentation and running costs.
The current status of the project, summarized in the draft reports of the task groups [5], leads to the schematic layout of the future facility presented in figure 6. The final report on the EURISOL project is expected in the end of 2003. 3. CONCLUSIONS The GANIL facility offers unique possibilities to study nuclei far from stability using both fragmentation-like (A
Nouvelles du GANIL, Hors Sdrie, GANIL, February 2002. E. Bouchez et al., Phys. Rev. Lett. 90 (2003) 082502. E. Bouchez PhD thesis 2003, Strasbourg University, to be published. SPIRAL II Web page, www.ganil.fr. EURISOL Web page, www.ganil.fr/eurisol.