Motivation

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


Motivation

Documents

kernstruktur physik

virtuellen photonenwhy

tested at the

intrinsic180 system

mode sfb

dalinac opera

dipole field distributionsfb

quadrupole magnet vacuum