Technical Design Report Super Fragment Separator

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2.4.1.2 General Description DRAFT The Super-FRS has to efficiently separate in-flight rare isotopes produced via projectile fragmentation of all primary beams up to 238 U and via fission of 238 U beams. The latter reaction is a prolific source of very neutron-rich nuclei of medium mass. However, due to the relatively large amount of kinetic energy released in the fission reaction, the products populate a large phase space and thus are one reason for the need of a much larger acceptance for the Super-FRS compared with the FRS, see Table 2.4.1. The gain in transmission for uranium fission products at the Super-FRS is more than an order of magnitude compared to the FRS [3]. Moreover, the Super-FRS provides similar gain factors for projectile fragments because of: 1) the required multiple energy-degrader stages for mono-isotopic spatial separation (Bρ-∆E-Bρ method), 2) the required enlargement of the primary beam spot at the power target for fast extraction, 3) the large momentum spread (σp/p ~ ±1%) of the incident fast extracted beam, 4) the option to produce the nuclides in secondary reactions at intermediate focal planes of the ion-optical system. Typical examples for the separation of projectile fragments with two degrader stages are illustrated in Figure 2.4.2. Figure 2.4.2: Transmission of the Super-FRS (at the MF4 focal plane) compared with the present FRS (at the S4 focal plane) for projectile fragmentation reactions. The fragment energy after the production target is 700 MeV/u and two Al degraders with a thickness of d/R = 0.5, 0.6 (in units of the atomic range of the fragment). The primary beams used for the reactions are indicated in the figure. The derived gain factors for the Super-FRS range from 1.5 (for the heaviest Z) to 16 (for the lighter Z). Besides the fragment intensities, the selectivity and sensitivity are crucial parameters that strongly influence the success of an experiment with very rare nuclei. A prerequisite for a clean isotopic separation is that the fragments have to be fully ionized to avoid cross contamination from different ionic charge states. Multiple separation stages are necessary to efficiently reduce the background from such contaminants. Based on the experience of successful spatial isotopic separation with the existing FRS at GSI, the Super-FRS also uses the Bρ-∆E-Bρ method, where a two-fold magnetic rigidity analysis is applied in front of and behind a specially shaped energy degrader. The strong enhancement of the primary beam intensity expected with the SIS100/300 synchrotron requires additional measures to achieve the required separation quality. A solution is at least one additional 8
DRAFT degrader stage which provides an effective pre-selection before the fragment beam impinges onto the main degrader. A straight forward consequence is that the Super-FRS consists of a two-stage magnetic system, the Pre- and the Main-Separator, each equipped with a degrader, having 6 intermediate focal planes. This condition for fully stripped fragments requires a high-energy operating domain. On the other hand, the thicknesses of the production target and degraders have to be optimized to prevent substantial losses due to secondary nuclear reactions. The selection of the maximum magnetic rigidity of 20 Tm results from these physical criteria, the optimization of the performance, costs of the magnetic elements and their dynamic range. 2.4.1.2.1 Ion-Optical Layout The ion-optical layout of the Super-FRS (High-Energy-Branch) and its imaging conditions are depicteed in Figure 2.4.3. The envelopes and the dispersion line are plotted for primary-beam emittances of 40 π mm mrad, and ∆p/p of ±2.5 %, respectively. The target spot size is assumed to be ±1 mm and ±2 mm in the x- and y-direction, respectively. The magnet system consists of the Pre-Separator and the Main-Separator, each equipped with an energy-degrader stage. The Pre- and Main-Separator are both achromatic systems, hence the complete system is also achromatic. This means the image size at the final focal plane is independent of the momentum spread of the fragments at the entrance of the system and thus guarantees the best spatial isotopic separation. Figure 2.4.3: Ion-optical elements, beam envelopes (full lines) and the dispersion line for 2.5 % momentum deviation (dashed line) are shown in the lattice of the Super-FRS. Here, the High-Energy-Branch (HEB) is presented. The envelopes result from an emittance of 40 π mm mrad in x and y direction. The different focal planes of the Pre-Separator (P) and the Main-Separator (M) are indicated by (P, M) F1–F4. Quadrupole triplets are placed in front of and behind the dipole magnets to achieve the desired ion-optical conditions at the focal planes and to properly illuminate the dipole magnets to achieve the required optical resolving power. Hexapole magnets and octupole correction coils which are superimposed to the quadrupole magnets are applied to correct image aberrations, especially at the degrader positions and the achromatic focal planes. The lengths of hexapole magnets and new dimensions of drift-lengths are main modifications compared to the previous design in the FAIR BTR. 9
Page 1 and 2: DRAFT Technical Design Report Super
Page 3 and 4: Preface DRAFT The International Fac
Page 5 and 6: Contents DRAFT 2.4.1 System Design
Page 7: DRAFT Table 2.4.1: Parameters of th
Page 11 and 12: Pre-Separator DRAFT In order to acc
Page 13 and 14: DRAFT coupling coefficients is give
Page 15 and 16: DRAFT Table 2.4.3: First-order matr
Page 17 and 18: DRAFT Main-Separator to the high-en
Page 19 and 20: DRAFT Table 2.4.5: Transmission T o
Page 21 and 22: DRAFT Figure 2.4.15: Resolution nec
Page 23 and 24: DRAFT Figure 2.4.17: Spectrometer m
Page 25 and 26: DRAFT Table 2.4.8: Design parameter
Page 27 and 28: DRAFT Figure 2.4.20: Side view of t
Page 29 and 30: DRAFT Figure 2.4.23: Coil cross-sec
Page 31 and 32: DRAFT Figure 2.4.25: Flux density d
Page 33 and 34: Figure 2.4.29: Assembly of two half
Page 35 and 36: DRAFT Figure 2.4.31: Cross section
Page 37 and 38: Figure 2.4.34: Sketch of the therma
Page 39 and 40: DRAFT To fulfill the required field
Page 41 and 42: DRAFT Figure 2.4.39: The 3D model o
Page 43 and 44: DRAFT Pole radius mm 100 210 250 25
Page 45 and 46: DRAFT Figure 2.4.43: Front, side, a
Page 47 and 48: ∆B/B 0.0 DRAFT Figure 2.4.46: Ave
Page 49 and 50: DRAFT Figure 2.4.50: 3D model of th
Page 51 and 52: DRAFT Figure 2.4.54 and Table 2.4.1
Page 53 and 54: DRAFT 2.4.2.3.1 Radiation resistant
Page 55 and 56: DRAFT The water-cooled radiator con
Page 57 and 58: DRAFT Table 2.4.17: Coil parameters
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DRAFT Figure 2.4.63: Field distribu
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DRAFT Figure 2.4.65: Multiplet conf
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DRAFT Table 2.4.21 summarizes the r
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2.4.2.6 Current Leads DRAFT The cur
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DRAFT Table 2.4.23 presents the lis
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2.4.3 Power Converters DRAFT The po
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SCR structure DRAFT Regarding high
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a) Chopper circuit 3x400V b) Half b
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External Control System Data transf
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DRAFT Figure 2.4.77: Arrangement of
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SuperFRS Power Supply Effective App
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DRAFT The locations for the differe
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DRAFT Figure 2.4.80: Beam induced f
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DRAFT Figure 2.4.82: Two hybrids ca
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DRAFT Figure 2.4.84: Left panel: TP
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DRAFT extracted beams. Its use for
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Time of Flight measurement DRAFT At
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DRAFT together. Another option is t
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DRAFT Figure 2.4.88: Pillow seal po
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DRAFT Figure 2.4.90: Setup at the m
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DRAFT An overview of the total vacu
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2.4.7.4 Appendix - Technical Drawin
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DRAFT Figure 2.4.96: Diagnostic cha
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DRAFT Figure 2.4.98: Diagnostic cha
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DRAFT Figure 2.4.100: Diagnostic ch
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2.4.8 Particles Sources n/a 2.4.9 E
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DRAFT movable, but BC3 must be able
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DRAFT Figure 2.4.106: Spot size of
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dE/dV [kJ/cm 3 ] 3 2 1 DRAFT includ
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2.4.11.1.4 Design of the beam catch
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DRAFT Figure 2.4.110: Calculated eq
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DRAFT Figure 2.4.112: Location of b
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DRAFT the carbon. Again mainly 7 Be
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DRAFT maintenance of the carbon or
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DRAFT material) and received the an
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DRAFT commissioned in February 2005
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DRAFT Table 2.4.28: Typical beam pa
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DRAFT Figure 2.4.120: Surface tempe
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DRAFT Figure 2.4.123: Schematic lay
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DRAFT These results show that the i
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DRAFT Like in the case of the rotat
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DRAFT Figure 2.4.126: Left: Schemat
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DRAFT Figure 2.4.129: Flow scheme o
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DRAFT Since the weight of the cold
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DRAFT With the cooling capacity spe
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DRAFT Figure 2.4.134: Schematic of
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S1 (a) Figure 2.4.136: (a) Zoom of
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2.4.A Appendix DRAFT The appendix o
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DRAFT experiment the EXL community
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2.4.A1.3 Slow control and monitorin
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DRAFT Figure 2.4.139: Architecture
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DRAFT all FAIR accelerators will be
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DRAFT source tier are split in two
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DRAFT coupled from the ACS which is
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DRAFT 2.4.A3.2 Work packages: descr
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2.4.A3.2.4 Instrumentation Measurin
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DRAFT this, planning a network layo
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DRAFT 2.4.A3.3 Machine characterist
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DRAFT installation of RALF was done
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DRAFT The double ring synchrotrons,
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DRAFT The first refrigerator, Cryo1
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DRAFT shield 28874 + 25 g/s 22 bar
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LHe storage Helium storage Helium s
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Cryo2 Cryo3 CryoST DB 3 DRAFT Compr
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DRAFT The cold connection will be m
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DRAFT Measurements planned for each
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DRAFT For magnets with less stringe
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DRAFT The value, parameters, condit
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DRAFT 3. Geometry tests For cryosta
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DRAFT The Quench Heaters Tests has
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DRAFT Figure 2.4.159: Photograph of
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DRAFT The field properties listed i
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DRAFT Figure 2.4.161: Schematic vie
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DRAFT Figure 2.4.162: Scheme of the
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2.4.A6.2.2 Shielding against direct
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DRAFT Figure 2.4.165: An iron beam
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DRAFT In a side view the flux of pr
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DRAFT catcher 7 Be, 22 Na and 24 Na
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DRAFT at the FRS (2·10 9 /spill as
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DRAFT [1] H. Geissel et al., Nucl.
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DRAFT [74] A. Fabich and J. Lettry,
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Technical Design Report Super Fragment Separator

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