Motivation Requirements Preliminary design Status Yaroslav Kalmykov Small Angle Magnet Institut für Kernphysik Technische Universität Darmstadt SFB 634

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


The eA Collider

Motivation


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


Why at the S-DALINAC?


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


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


SpectrometerDipole

DetectorPlane

SeparatingMagnet

Target

0

0

0

Coupling of “horizontal” and “vertical” optics

Background Sources in the 180° Mode


IncidentBeam

Target

Faraday Cup

40º System

RefocusingQuadrupoles

169º Spectrometer

0 4 m

Time of flight measurement

Excitation Energy Spectrum of 12C


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


Preliminary Design: Layout


Calculations: Dipole Field Distribution


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)


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)


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?


Preliminary Design: Parameters


Documents

Motivation Requirements Preliminary design Status Yaroslav Kalmykov Small Angle Magnet Institut für Kernphysik Technische Universität Darmstadt SFB 634