Technical Design Report Super Fragment Separator

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DRAFT Fast-extracted beams on a graphite wheel target In view of the complexity of the operation of a liquid-metal target, it is desirable to use the rotating-wheel target also for fast-extracted beams, as long as the critical parameters of graphite (temperature, pressure) are not exceeded. This will be the case for low-Z projectile particles or low beam intensities. Since the beam intensity at the FAIR facility will increase gradually in different steps, one could use this option during the early phases. In case of the highest beam intensities one can achieve lower-specific-energy conditions by extending the beam-spot size. In this context it is important to remember that a wider beam spot in the dispersive (x-) direction will deteriorate the ion-optical resolution, see Figure 2.4.13. An extended beam spot in y-direction will not affect the resolution but reduce the transmission. Going to σy = 12 mm instead of 2 mm will reduce the transmission into the CR without changes in the optics by a factor of three. In order to operate a graphite wheel in the fast-extraction mode, there are several critical questions to be answered: • What are the maxima (positive and negative) of the pressure waves that traverse a graphite target after the impact of the short ion pulse? • What are the technical limits of these pressure peaks that allow safe operation? Since the technically acceptable operating temperature is about 1800 °C [65], one would need to know the limiting pressure values at this temperature. First calculations were performed with the 2-dimensional code BIG-2 [72] for three different benchmark beams: argon, xenon and uranium. For each of these beams, different cases were studied using different beam intensities – 10 10 , 10 11 , 10 12 ions/spill, and different sizes of the beam spot with σx = 1mm and σy = 2, 6, 12 mm assuming two-dimensional Gaussian shapes. In each case, the single spill was assumed to have a length of 50 ns while the beam energy was taken to be 1 A GeV. For the uranium beam a target thickness of 3 g/cm 2 was assumed, while for the two other beams it was 8 g/cm 2 . Calculations were performed for both, single-shot and multiple-shot cases. Details of the calculations are given in Ref. [72]; here only a summary of results is presented. The limiting values of temperature and pressure defining the regime where the target would survive a single shot are taken as T = 2000 K and P = 150 MPa 2 , respectively. For 10 10 ions/spill, the target would survive the irradiation with all three beams having nominal sizes of σx = 1 mm, σy = 2 mm. In the case of 10 11 ions/spill, the target would survive an argon beam with σy = 2 mm and a xenon beam with σy = 6 mm, while none of the beam-spot sizes considered is acceptable for uranium. For the highest intensity of 10 12 ions/spill and nominal beam spot sizes of σx =1 mm, σy = 2 mm, only in the case of argon the graphite target would survive a single shot. For the two other beams the pressure and/or the temperature are above the critical limits for all three beam-spot sizes considered. In order to use a solid graphite target with the highest intensity, calculations have shown that one would need σx = 2.5 mm, σy = 12 mm for xenon and σx = 4 mm, σy = 12 mm for uranium [72]. This would, on the other hand, decrease the resolving power of the Super-FRS. For these cases, one should consider to use the liquid-metal jet target. 2 For the preliminary calculations presented in this report, a critical pressure value of 150 MPa is assumed. Since a detailed study on values of critical parameters is under way, some conclusions on the operating regime might change. 136
DRAFT These results show that the identical graphite wheel which will be used for slowly extracted beams can serve as a good option to perform experiments with high-power fast-extracted beams, too. Nevertheless, due to the enlarged beam spot at the production target the transmission and the separation power of the Super-FRS are restricted in this operation mode, especially for the experiments using uranium primary beams. More refined thermo-mechanical calculations will be performed in the future to verify the estimates mentioned above. Liquid-metal jet as a target for fast-extracted beams The very high instantaneous power deposited by a well focussed full-intensity uranium beam in fast extraction will lead to instantaneous destruction of solid materials. An alternative solution may be a windowless liquid-metal target. The following liquid metals can be considered as potential targets for Super-FRS: light ones (Li, Na), medium-heavy ones (Ga), and heavy ones (Hg, Pb). The physical properties of some of the possible target materials are given in Table 2.4.30. Only pure elements are considered, since eutectics can be elementally separated during irradiation. Lower-Z targets (Li,Na) are preferable due to lower multiple scattering of radioactive nuclides, higher number of atoms per unit energy loss of the primary beam, and smaller range of long-lived radioactive products. Table 2.4.30: Physical properties of several materials considered as liquid-metal jet targets for fast extraction. Target Density of liquid [75] [g/cm 3 ] Melting point[76] [ o C] Boiling point [76] [ o C] a Thermal conductivity [75] [W m -1 o C -1 ] b Vapour pressure [77] [Pa] c Sound velocity [76] [m/s] a Specific heat [75] [J kg -1 o C -1 Li 0.508 180.54 1342 42.258 1.63·10 ] -8 6000 4226 Na 0.930 97.72 883 84.517 1.33·10 -5 3200 1381 Ga 6.090 29.76 2204 33.472 9.31·10 -36 2740 398.7 Hg 13.500 -38.83 356.73 8.368 2·10 -4 1407 138.1 Pb 10.600 327.46 1749 16.318 4.21·10 -7 1260 150.6 a Value given for the liquid state. b Value of the vapour pressure is given for all materials but Na at the corresponding melting-point temperature. For Na, the value is given at T = 961 o C. c Except for mercury, the values are given for the given material in solid state. A definite decision on the material for the liquid jet will be made after detailed investigations of the hydro-dynamical and chemical behaviour of the considered materials have been performed. Calculation of jet response to fast beam pulses For the first test calculations, a jet made of liquid lithium was assumed. Two different theoretical approaches were taken. In the first approach [72], the response of a liquid-lithium jet to a high-intensity 238 U beam pulse of 50 ns length has been calculated with a 2-dimensional hydro-dynamical code, BIG-2 [78]. The benchmark Super-FRS beam, 10 12 238 U ions with 1 A GeV 137
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DRAFT Technical Design Report Super
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Preface DRAFT The International Fac
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Contents DRAFT 2.4.1 System Design
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DRAFT Table 2.4.1: Parameters of th
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DRAFT degrader stage which provides
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Pre-Separator DRAFT In order to acc
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DRAFT coupling coefficients is give
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DRAFT Table 2.4.3: First-order matr
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DRAFT Main-Separator to the high-en
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DRAFT Table 2.4.5: Transmission T o
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DRAFT Figure 2.4.15: Resolution nec
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DRAFT Figure 2.4.17: Spectrometer m
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DRAFT Table 2.4.8: Design parameter
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DRAFT Figure 2.4.20: Side view of t
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DRAFT Figure 2.4.23: Coil cross-sec
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DRAFT Figure 2.4.25: Flux density d
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Figure 2.4.29: Assembly of two half
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DRAFT Figure 2.4.31: Cross section
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Figure 2.4.34: Sketch of the therma
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DRAFT To fulfill the required field
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DRAFT Figure 2.4.39: The 3D model o
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DRAFT Pole radius mm 100 210 250 25
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DRAFT Figure 2.4.43: Front, side, a
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∆B/B 0.0 DRAFT Figure 2.4.46: Ave
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DRAFT Figure 2.4.50: 3D model of th
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DRAFT Figure 2.4.54 and Table 2.4.1
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DRAFT 2.4.2.3.1 Radiation resistant
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DRAFT The water-cooled radiator con
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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
Page 85 and 86: DRAFT Figure 2.4.82: Two hybrids ca
Page 87 and 88: DRAFT Figure 2.4.84: Left panel: TP
Page 89 and 90: DRAFT extracted beams. Its use for
Page 91 and 92: Time of Flight measurement DRAFT At
Page 93 and 94: DRAFT together. Another option is t
Page 95 and 96: DRAFT Figure 2.4.88: Pillow seal po
Page 97 and 98: DRAFT Figure 2.4.90: Setup at the m
Page 99 and 100: DRAFT An overview of the total vacu
Page 101 and 102: 2.4.7.4 Appendix - Technical Drawin
Page 103 and 104: DRAFT Figure 2.4.96: Diagnostic cha
Page 105 and 106: DRAFT Figure 2.4.98: Diagnostic cha
Page 107 and 108: DRAFT Figure 2.4.100: Diagnostic ch
Page 109 and 110: 2.4.8 Particles Sources n/a 2.4.9 E
Page 111 and 112: DRAFT movable, but BC3 must be able
Page 113 and 114: DRAFT Figure 2.4.106: Spot size of
Page 115 and 116: dE/dV [kJ/cm 3 ] 3 2 1 DRAFT includ
Page 117 and 118: 2.4.11.1.4 Design of the beam catch
Page 119 and 120: DRAFT Figure 2.4.110: Calculated eq
Page 121 and 122: DRAFT Figure 2.4.112: Location of b
Page 123 and 124: DRAFT the carbon. Again mainly 7 Be
Page 125 and 126: DRAFT maintenance of the carbon or
Page 127 and 128: DRAFT material) and received the an
Page 129 and 130: DRAFT commissioned in February 2005
Page 131 and 132: DRAFT Table 2.4.28: Typical beam pa
Page 133 and 134: DRAFT Figure 2.4.120: Surface tempe
Page 135: DRAFT Figure 2.4.123: Schematic lay
Page 139 and 140: DRAFT Like in the case of the rotat
Page 141 and 142: DRAFT Figure 2.4.126: Left: Schemat
Page 143 and 144: DRAFT Figure 2.4.128: Schematic lay
Page 145 and 146: DRAFT Figure 2.4.129: Flow scheme o
Page 147 and 148: DRAFT Since the weight of the cold
Page 149 and 150: DRAFT With the cooling capacity spe
Page 151 and 152: DRAFT Figure 2.4.134: Schematic of
Page 153 and 154: S1 (a) Figure 2.4.136: (a) Zoom of
Page 155 and 156: 2.4.A Appendix DRAFT The appendix o
Page 157 and 158: DRAFT experiment the EXL community
Page 159 and 160: 2.4.A1.3 Slow control and monitorin
Page 161 and 162: DRAFT Figure 2.4.139: Architecture
Page 163 and 164: DRAFT all FAIR accelerators will be
Page 165 and 166: DRAFT source tier are split in two
Page 167 and 168: DRAFT coupled from the ACS which is
Page 169 and 170: DRAFT 2.4.A3.2 Work packages: descr
Page 171 and 172: 2.4.A3.2.4 Instrumentation Measurin
Page 173 and 174: DRAFT this, planning a network layo
Page 175 and 176: DRAFT 2.4.A3.3 Machine characterist
Page 177 and 178: DRAFT installation of RALF was done
Page 179 and 180: DRAFT The double ring synchrotrons,
Page 181 and 182: DRAFT The first refrigerator, Cryo1
Page 183 and 184: DRAFT shield 28874 + 25 g/s 22 bar
Page 185 and 186: 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 2.4.164: Schematic lay
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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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