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Motivation
Requirements
Preliminary design
Status
Yaroslav Kalmykov
Small Angle Magnet
Institut für Kernphysik
Technische Universität Darmstadt
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
180° System at the S-DALINAC
OPERA-2d simulations
Motivation
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
The eA Collider
Motivation
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
Feasibility of electron scattering at very forward angles can be tested at the S-DALINAC
S. Strauch et al., PRL 85 (2000) 2913
Fixed target Collider
48Ca(e,e‘n) 48Ca(e,e‘A‘)
n 100msr 100 n 4
neff 20 % 5 neff 100 %
e‘ = 40 ° 50 e‘ = 5 °
103-104
L=1031 - 1032 cm-2 s-1 L 1028
Motivation
- Selectivity? 22qFVqFV
dd
TTLL
10-8
10-4
100
104
0 45 90 135 180 (deg)
12C(e,e )E =60 MeV
’0
VT
VL
E =10 MeVx
VL
()
VT
E
Coincidence detectors
- 2π Liquid scintillator
- Si-Ball
- BaF
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
Why at the S-DALINAC?
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
S-DALINAC 22 ≤ E0 ≤ 120 MeV for (e,e’)
I ≤ 5 A for (e,e’)
180° System = 6.4 msr≤ p/p ≤ 8%E/E = 2 x 10-4 (intrinsic)
QCLAM spectrometer = 35 msr p/p = ± 10%E/E = 2 x 10-4 (intrinsic)
180° System at the S-DALINAC
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
Incident Beam
Chicane
ScatteringChamber
SeparatingMagnet
Target
DeflectingCoils
To Faraday Cup
QCLAM Spectrometer
25°
155° - 132.5°
25°
0 1 m
RefocusingQuadrupoles
Electron Trajectories in the 180° Mode
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
SpectrometerDipole
DetectorPlane
SeparatingMagnet
Target
0
0
0
Coupling of “horizontal” and “vertical” optics
Background Sources in the 180° Mode
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
IncidentBeam
Target
Faraday Cup
40º System
RefocusingQuadrupoles
169º Spectrometer
0 4 m
Time of flight measurement
Excitation Energy Spectrum of 12C
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
12C(e,e’)
E = 73 MeV
= 180°
0
1+
2+
Cou
nts
Excitation Energy (MeV)
FWHM = 80 keV
Requirements
Incident beam energy : ≤ 80 MeV
e-
TargetSpectrometer Bending magnet
Scattering at very forward angles
Momentum transfer : ≈ 0
Spectrometer angle : ≥ 25°
Scattering chamber : Ø 582 mm
Target position
Beam broadening
B
Quadrupole magnet
Vacuum SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
Preliminary Design: Layout
Dipole and quadrupole components
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
Preliminary Design: Layout
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
Calculations: Dipole Field Distribution
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
Calculations: Dipole Field Distribution
OPERA-2dPre and Post-Processor 8.700
15/Nov/2002 15:03:17 Page 37
UNITSLength : m Flux density : T Field strength : A m -1
Potential : Wb m-1
Conductivity : S m-1
Source density : A m -2
Power : W Force : N Energy : J Mass : kg
PROBLEM DATAmy7th.stQuadratic elementsXY symmetryVector potentialMagnetic fieldsStatic solutionScale factor = 1.0 3944 elements 8019 nodes 7 regions
X coordY coord
0.00.0
0.020.0
0.040.0
0.060.0
0.080.0
0.10.0
0.120.0
0.140.0
0.160.0
0.180.0
0.20.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Values of BY
By
(T)
X (m)
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
Calculations: Quadrupole Field Distribution
OPERA-2dPre and Post-Processor 8.700
15/Nov/2002 14:59:48 Page 36
UNITSLength : m Flux density : T Field strength : A m -1
Potential : Wb m-1
Conductivity : S m-1
Source density : A m -2
Power : W Force : N Energy : J Mass : kg
PROBLEM DATAmy7th.stQuadratic elementsXY symmetryVector potentialMagnetic fieldsStatic solutionScale factor = 1.0 3944 elements 8019 nodes 7 regions
Angle Radius: 0.01, center: (0.0,0.0)
0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0
0.19312
0.19316
0.1932
0.19324
0.19328
0.19332
0.19336
0.1934
Values of BMOD
B (
T)
(deg)
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
Status
OPERA-2d simulations- Two-dimensional field distribution- Feasibility
General layout- Mechanical dimensions and position
Beam transport- Focus?- Background sources?
OPERA-3d simulations- Three-dimensional field distribution
Ion-optical properties (SAM + QCLAM)- Momentum acceptance?- Energy resolution?- Solid angle acceptance?- Scattering angle resolution?
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen
Preliminary Design: Parameters
SFB 634 – A2: Kernstruktur Physik mit virtuellen Photonen