Møller
This presentation is the property of its rightful owner.
Sponsored Links
1 / 30

Patricia Aguar Bartolomé , Kurt Aulenbacher , Valery Tioukin , Jürgen Diefenbach PowerPoint PPT Presentation


  • 50 Views
  • Uploaded on
  • Presentation posted in: General

Møller Polarimetry with Polarized Atomic Hydrogen at MESA. Patricia Aguar Bartolomé , Kurt Aulenbacher , Valery Tioukin , Jürgen Diefenbach Institut für Kernphysik , Universität Mainz PAVI’14, Syracuse, NY 17th July 2014. Outline. Physics Motivation

Download Presentation

Patricia Aguar Bartolomé , Kurt Aulenbacher , Valery Tioukin , Jürgen Diefenbach

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

MøllerPolarimetry with Polarized

Atomic Hydrogen at MESA

Patricia AguarBartolomé, Kurt Aulenbacher, Valery Tioukin, Jürgen Diefenbach

InstitutfürKernphysik, UniversitätMainz

PAVI’14, Syracuse, NY

17th July 2014

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Outline

  • Physics Motivation

  • Polarized Atomic Hydrogen Target

  • Status of the Mainz Hydro-MøllerTarget

  • Beam Stabilization Test

  • Summary

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Physics Motivation

Goal: Low energy PV electron scattering experiments at MESA with

systematic accuracy < 0.5% for beam polarization measurements

Hydro-Møller

PV

Detector

MESA (Mainz Energy recovering Superconducting Accelerator)

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Physics Motivation

Polarimetry Methods

  • ComptonScattering:Accurateenough at Ebeam > 4GeV, butaccuracy

  • around1% at lowenergiesNotenoughfor PV-experiments

  • MøllerScatteringwithferromagnetic target

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Physics Motivation

PolarimetryMethods

  • MøllerScatteringwithpolarizedatomichydrogen gas, stored in

  • a ultra-coldmagnetictrap

  • E.Chudakov and V.Luppov IEEE Trans. on Nucl. Sc., 51, 1533 (2004)

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Polarized Atomic Hydrogen Target

Magneticfield B splits H1groundstate

At B = 8T, sinq≈0.3%

Mixingangle tan2q ≈ 0.05/B(T)

Mixture ~ 53% of and ~ 47% of , Pe ~ 1-d,  ~ 10-5

Storage Cell

  • In a field gradient a force

  • Pulls,intothestrongfield

  • Repels,out of thestrongfield

H+H H2

  • recombination(releasing ~ 4.5 eV)

  • higherat lowT cellwallscoatedwith ~50nm

  • superfluid4He

  • Gas density: cm-3

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Dilution Refrigerator and Magnet

T=300mK of theatomictrap can be reachedusing a DilutionRefrigerator

and therequieredB=8Tusing a superconductingsolenoid

Dilutionrefrigerator and magnet

shippedfrom UVA toMainz

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Status of the Atomic Hydrogen Target

New DilutionRefrigeratorneeds

tobedesigned and produced!!

Test superconductingsolenoid

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Status of the Atomic Hydrogen Target

UVA SuperconductingSolenoidTest

  • 8 thermo sensors (4 Pt-100, Pt-1000, Si-Diode, 2 Cernox) placed in different

  • points of the solenoid

  • Several tests with Nitrogen (T~77K) were successfully performed

  • Infeasible Helium (T~4K) test due to the appearance of a big leakrate

  • New cooling set up for the solenoid needs to be designed and produced

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Status of the 8T Superconducting Magnet

New coolingsystemsetup design

  • Most of the new cooling system

  • componentscurrently under

  • construction

  • Estimated time to assemble

  • the new set up ~ August

  • Cooling down of the magnet

  • with Helium ~ September

Vacuum

Vessel

Courtesy of J.Bibo and D. Rodriguez

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Status of the 8T Superconducting Magnet

New coolingsystemsetup design

  • Most of the new cooling system

  • components currently under

  • construction

  • Estimated time to assemble

  • the new set up ~ August

  • Cooling down of the magnet

  • with Helium ~ September

Copper Shields

(T ~77K)

Courtesy of J.Bibo and D. Rodriguez

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Status of the 8T Superconducting Magnet

New coolingsystemsetup design

  • Most of the new cooling system

  • components currently under

  • construction

  • Estimated time to assemble

  • the new set up ~ August

  • Cooling down of the magnet

  • with Helium ~ September

Solenoid

(T~4K)

Courtesy of J.Bibo and D. Rodriguez

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Status of the 8T Superconducting Magnet

New coolingsystemsetup design

  • Most of the new cooling system

  • components currently under

  • construction

  • Estimated time to assemble

  • the new set up ~ August

  • Cooling down of the magnet

  • with Helium ~ September

Courtesy of J.Bibo and D. Rodriguez

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Status of the 8T Superconducting Magnet

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Status of the Atomic Hydrogen Target

Preliminary design of the new Dilution Refrigerator

  • General considerations

  • Lowtemperature (T=300mK) and highcoolingpower (Q=75-100mW)

  • Optimizationby a carefulcalculation:

  • - Heatexchangers

  • - Pressuredrop in thepumpinglines

  • - Condensation of the mixture

  • - Amount of 3He and 4He gas needed

  • - Volumes of allpartsinsidethe DR (separator, evaporator,

  • still) and alsopumps and lines

  • - Produce new mixingchamber

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Status of the Atomic Hydrogen Target

Preliminarydesign of the new DilutionRefrigerator

  • HeatExchangers (HE)

  • Design of the HE is of majorimportance. Theimportantparameters

  • are:

  • 1. Small volumetoreachtheequilibriumtemperatureveryfast

  • 2. Small thermalresistancebetweenthestreamstogetgood

  • temperatureequilibriumbetweenthem

  • Imperfections and impurities can influencethetransport of heat

  • Thermalboundaryresistancebetweenhelium and the HE material

  • at T<1K Kapitzaresistance~ T3

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Status of the Atomic Hydrogen Target

Preliminarydesign of the new DilutionRefrigerator

1.1K stage HE currentlyunder

construction in ourMechanical

Workshop

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Beam Stabilization for PV experiments

Requirementsforthe PV experiment at MESA

  • P2 expectedphysicsasymmetry< 50 ppb

  • Beamenergy~ 150 MeV(externalbeam)

  • DPB/PB ≤ 0.5%

  • Beamquality:

  • Beammustbestabilized(DAi0)

  • Helicitycorrelationsmustbesuppressed(Ai 0)

  • Beamparameters are correlatedwithhelicityAi

  • Noiseonbeamparameters (helicity un-correlated) DAi

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Beam Stabilization

Beam stabilization and solenoid test set up

Reliable 3T solenoidfor first tests

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Beam Stabilization

Principle of beamstabilization

  • Cavitymonitorsmeasurebeam position (XYMOs)

  • Steeringmagnetscorrectbeamdirection (WEDLs)

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Beam Stabilization

Beamtestswithsolenoid

  • Use anavailable 3T superconductingsolenoid

  • Gainexperiencesteering <200 MeVbeamthrough a superconductingsolenoid

  • Operatebeam position/anglestabilizationacrossthesolenoid

  • Mostrealistic test of polarimetry+beamstabilizationfor P2 possiblebefore

  • MESA is in operation

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Summary/Outlook

  • PV electronscatteringexperiments at MESA are planned

  • systematicaccuracy of < 0.5% forthebeampolaizationmeasurements

  • AtomicHydrogen gas, stored in a ultra-coldmagnetictrap can provide

  • thisaccuracy

  • A solenoid and a dilutionrefrigeratorwereshippedfromtheUniversity

  • of Virginia toMainz

  • New coolingdownsetupof thesolenoidand new DR design and

  • productionisin progress

  • Productionof a new mixingchamberand a atomichydrogendissociator

  • isalsorequired

  • Beamstabilization test isplannedwithinthenextyear

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

BACKUP

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Beam Stabilization

PlannedBeam test setup

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Beam Stalilization

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Beam Stalilization

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Polarized Atomic Hydrogen Target

Gas Lifetime in the Cell

  • Loss of hydrogen atoms from the cell due to:

  • Thermal escape through the magnetic field gradient dominates at T > 0.55 K

  • Recombination in the gas volume negligible up to densities of ~1017 cm-3

  • Recombination in the cell surface constant feeding the cell with atomic

  • hydrogen

E.Chudakov and V.Luppov IEEE Trans. on Nucl. Sc., 51, 1533 (2004)

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Polarized Atomic Hydrogen Target

Contamination and Depolarization of the Target Gas

No Beam

  • Hydrogenmolecules~ 10-5

  • High energyatomicstates and < 10-16

  • Excitedatomicstates< 10-5

  • Helium and residual gas < 0.1% empty target measurement

  • withthebeam

Beam Impact

  • Depolarization by beam generated RF field

  • Gas heating by beam ionization losses < 10-10

  • Depolarized ions and electrons contamination < 10-5

  • Contamination by excited atoms < 10-5

Expecteddepolarization

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Polarized Atomic Hydrogen Target

Dynamic Equilibrium and Proton Polarization

As a result, the cell contains predominantly

In a dynamic equilibrium, P ~ 80 % in about 10 min.

Patricia Aguar Bartolome - PAVI'14


Patricia aguar bartolom kurt aulenbacher valery tioukin j rgen diefenbach

Physics Principles of the DR

Cooling power:

Below 0.3K the dilution refrigerator has much higher cooling power

Patricia Aguar Bartolome - PAVI'14


  • Login