Technical Design Report Super Fragment Separator

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DRAFT possibility to perform a current measurement here, which becomes favourable due to the uniformity of the pulse heights. 2.4.6.5 In-flight fragment identification (Bρ, ∆E, ToF) Magnetic rigidity measurement The magnetic rigidity can be deduced from a position measurement in the dispersive planes, two scenarios are considered: (a) determination during setup (b) continuous monitoring. Option (a) requires a good knowledge of the relative magnetic field as a pilot beam is centred with known Bρ, and the measured B-field can be calibrated using an effective radius for the dipole magnets. Unknown magnetic rigidities can thus be determined. The centring process can be done at reduced rate using the standard detectors (see sections 2.4.6.2 and 2.4.6.3). Option (b) is more demanding but also required by several NUSTAR experiments (e.g. the R³B collaboration). The idea is here to gather additional information on the incoming beam by measuring its displacement in the dispersive plane (MF2) of the separator event-by-event. This method [35] has been successfully applied at the FRS to improve the mass resolution in the ALADIN-LAND reaction setup for fission fragments that were transferred to Cave B, by using a scintillator strip array. The granularity of the strip setup determines the maximum rate that can be dealt with typically a few MHz/strip. Instead of this conservative approach the use of PC-CVC-DD would be advantageous. For this latter approach, a rate capability of 100 MHz/mm could be reached with a 300-500 µm thick detector array, polished to a roughness that is below 10 µm – which is consistent with the 3 % accuracy specified by the manufacturers – to avoid a degradation of resolution due to a lack of detector homogeneity. Precise water-dive measurements performed in early PC-CVD-DD research show that even PC-CVD as grown diamond material is tight, meaning without serious amount of pinholes: no water absorption has been measured [36]. This is an indication that it is valid to assume roughly the diamond mass density to 3.5 g/cm 3 over the whole bulk. However, the much higher concentration of grain boundaries in the nucleation side of the film may lead to residual graphite material (ρgraphite ≈ 2.2 g/cm 3 ) on this side which can reduce the average density. R&D work is underway at the FRS to ensure quality of the PC-CVD material. Details for the diamond detector setup can be found below. The online monitoring of the stability of the separator settings will be used for feedback loops to perform e.g. automatic centring through the setup. This requires a combined analysis and simulation framework in order to be able to determine the offsets and compute the corrections. Here accelerator controls and Super-FRS instrumentation have to be coupled in the most efficient way. Specific energy loss measurement For the required charge resolution via the specific energy loss we consider MUSIC (multiple sampling ionization chamber [37] detectors as the optimal choice. These detectors can currently measure rates up to 200 kHz. There are developments underway to increase these rates up to a few MHz [38]. These detectors will be positioned at the foci MF(2, 4, 7, 10) with an active area of (40 x 8) cm², and be operated continuously at the final focal planes to identify fragments during experiments. 90
Time of Flight measurement DRAFT At present plastic scintillator detectors are being used in the FRS to perform the TOF measurement, leading to a restriction in rate of a few MHz on the detector. In the dispersive plane of the FRS this problem can partly be overcome by using a segmented scintillator strip detector. For the Super-FRS, we will investigate also the possible use of diamond detectors, providing both position information and timing signals at the MF(2, 4, 7, 10) focal planes with an active area of (40 x 5) cm² using a pitch of 1 mm. For the foreseen rates these detectors would be optimal with respect to rate capability and radiation hardness. Using various heavy projectiles the intrinsic time resolution of PC-CVD-DDs has been measured frequently to be well below 50 ps. Recently, the FOPI collaboration achieved a σintr = 22 ps with 181 Ta ions of 1 GeV/u (Figure 2.4.87). A similar value (σintr = 29 ps) has been measured in the HADES setup using 52 Cr ions of 650 MeV/u. Figure 2.4.87: Intrinsic time resolution of PC-CVD-DDs demonstrated using 181 Ta ions at 1 GeV/u. (PRELIMINARY data, measured by the FOPI Collaboration). Time spectrum measured with two PC DG diamond detectors of a thickness of 500 µm mounted perpendicular to the primary beam (left), compared to the time spectrum measured with one diamond against the time given by the currently used FOPI start detector (plastic scintillator detector, right). At PF4 (see section 2.4.6.3) a (4 x 4) cm² PC/SC-CVD-DD can be used also as time-of-flight detector whenever suitable. The time resolution of SC-CVD-DDs is expected to be at least as good as for PC material. The electronics used in the FOPI run consisted of a 16 channel front end board with preamplifiers designed for RPC readout, and a version for scintillator detectors also exists. These boards can be coupled to the GSI Tacquila front end readout system [39], that provides excellent time resolution at a moderate channel costs. Apart from TAC based systems, the GSI ASIC group is developing DLL based solutions [40] for fast timing measurements that provide the envisaged resolutions with the advantage of being inherently free from the need of an external calibration. 2.4.6.6 Data acquisition The main task of the Super-FRS data acquisition (DAQ) is to provide on-line data about the production and separation process in the separator. It is clear from the beginning, that there are rate limitations, that will set the limit between event-by-event and integrated data. For different experiments in the experimental branches different classes of information are required. 91
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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
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
Page 59 and 60: DRAFT Figure 2.4.63: Field distribu
Page 61 and 62: DRAFT Figure 2.4.65: Multiplet conf
Page 63 and 64: DRAFT Table 2.4.21 summarizes the r
Page 65 and 66: 2.4.2.6 Current Leads DRAFT The cur
Page 67 and 68: DRAFT Table 2.4.23 presents the lis
Page 69 and 70: 2.4.3 Power Converters DRAFT The po
Page 71 and 72: SCR structure DRAFT Regarding high
Page 73 and 74: a) Chopper circuit 3x400V b) Half b
Page 75 and 76: External Control System Data transf
Page 77 and 78: DRAFT Figure 2.4.77: Arrangement of
Page 79 and 80: SuperFRS Power Supply Effective App
Page 81 and 82: DRAFT The locations for the differe
Page 83 and 84: 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: DRAFT extracted beams. Its use for
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 and 136: DRAFT Figure 2.4.123: Schematic lay
Page 137 and 138: DRAFT These results show that the i
Page 139 and 140: 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 2.4.128: Schematic lay
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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 2.4.164: 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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