Nuclear physics:the ISOLDE facility

Magdalena KowalskaCERN, PH-Dept.

kowalska@cern.ch

on behalf of the CERN ISOLDE teamwww.cern.ch/isolde

Lecture 2: CERN-ISOLDE facility

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Outline

Lecture 1: Introduction to nuclear physics

This lecture: CERN-ISOLDE facility Types of radioactive ion beam facilities ISOLDE within CERN Beam production at ISOLDE

Lecture 3: Physics of ISOLDE

Aimed at both physics and non-physics students

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Open questions in nuclear physics2 kinds of interacting fermions

How to answer the questions:Study nuclei with very different numbers of protons and neutrons

(NuPECC long-range plan 2010)

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RIB facilities

Light beam

heavy beam

Two main types of (complementary) RIB facilities: ISOL (Isotope Separation On-Line) and In-Flight

RIB:Radioactive Ion BeamRare Isotope Beam

RIB facilities comparison

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ISOL In-FlightProjectile light heavyTarget thick thinIon beam energy low highBeam intensity high lowVariety of nuclides smaller largeRelease from target slow fast

Beam quality good poorExamples ISOLDE@CERN,

SPIRAL@GANIL,ISAAC@TRIUMF

GANIL, GSI, RIKEN, NSCL/MSU

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RIB facilities worldwideExisting and in preparation

After B. Sherill

ISOL-typeIn-Flight

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ISOLDE – short historyFirst beam October 1967

New facility June 1992

Upgrades 1974 and 1988

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ISOLDE at CERN

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ISOLDE within CERN accelerators

LINAC2

PSB

PS

ISOLDE

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ISOLDE elementsIsotope production via reactions of light beam with thick and heavy target

Production – ionization – separation

Target

Separator

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Ion beam intensityNumber of extracted ions (yield) is governed by:

According to Ulli Koester:

primary particle flux x reaction cross section x number of target particles x efficiencies

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Production channels

1 GeV p

pn

238U

201Fr

+spallation

11Li X

+ +fragmentation

143Cs Y

+ +fission

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Production targets Over 20 target materials and ionizers, depending on beam of interestU, Ta, Zr, Y, Ti, Si, …Target material and transfer tube heated to 1500 – 2000 degreesOperated by robots due to radiation

Converter Target Standard

Converter

Target

Target

p+p+p+

p+p+p+

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Inside a standard target

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Ionization SurfacePlasmaLasers

After U. Koester

Beam extraction and separation All produced ions are extracted by electrostatic field (up to 60kV)

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The interesting nuclei are mass selected via magnetic field Lorentz force: depends on velocity and mass m/dm <5000, so many unwanted isobars also get to experiments

=

To experiments

=

U

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Production, ionization, extraction target Target+ vacuum+ extraction

robots Ion energy: 30-60keV

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Separation

Magnet separators (General Purpose and High Resolution)

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Post-accelerationREX accelerator Ion trapping

and coolingIncrease in charge state

A/q selectionRf acceleration

3MeV*A beam to experiment

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Production and selection - exampleFa

cilit

y

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Example – astatine isotopes

S. Rothe et al, Nature Communications 4 (2013), 1835

How to produce pure beams of astatine isotopes (all are radioactive)? Use lasers to ionize them

And determine for the first time the At ionization potential

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Extracted nuclidesMore than 700 nuclides of over 70 chemical elements delivered to users – by far largest choice among ISOL-type facilities (experience gathered over 40 years)

Experimental hallTarget stations

HRS & GPS

Mass-sep.HRS

ISCOOLRILISREX-ISOLDE

PS-Booster 1.4 GeV protons

3×1013 ppp

ISOLTRAP

CRIS

COLLAPS

NICOLE

MINIBALL and T-REX

WITCH

Travelling setups

Travelling setups

Post-accelerated beams

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Decay spectroscopyCoulomb excitationTransfer reactionsLaser spectroscopyBeta-NMRPenning traps

Collection points

TAS

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Facility photos

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Experimental beamlines

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HIE-ISOLDE upgradeHigh Intensity and

Energy ISOLDE

Works on-goingFirst post-accelerated beam in 2015/2016

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ISOLDE physics topics

Nuclear PhysicsNuclear Decay Spectroscopy

and ReactionsStructure of Nuclei

Exotic Decay Modes

Atomic PhysicsLaser Spectroscopy and

Direct Mass Measurements

Radii, Moments, Nuclear Binding Energies

Nuclear Astrophysics

Dedicated Nuclear Decay/Reaction Studies

Element Synthesis, Solar Processes

f(N,Z)

Fundamental PhysicsDirect Mass Measurements,

Dedicated Decay Studies - WICKM unitarity tests, search for b-n correlations, right-handed

currents

Applied PhysicsImplanted Radioactive Probes, Tailored Isotopes for Diagnosis

and Therapy Condensed matter physics and

Life sciences

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Summary Two complementary types of RIB facilities ISOL and in-flight Several dozen facilities worldwide and new ones coming

ISOLDE at CERN ISOL-type facility which uses protons from PSB Elements: production target, ionization, extraction, separation, (post-

acceleration) Largest variety of beams worldwide Upgrade project: HIE-ISOLDE

ISOLDE research topics: Nuclear physics Atomic physics Nuclear astrophysics Fundamental studies Applications => Lecture 3

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Reaction probability

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Reaction probabilityPrimary beam type and energy are important

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Research with radionuclidesNuclear physics Strong interaction in many-nucleon systems Nuclear driplines

Astrophysics Nucleo-synthesis, star evolution Abundances of elements

Applications, e.g. Solid state physics, life sciences

?= Mean

field

2820

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2s-shell

p-shell

sd-shell

fp-shell

34Ne: 10 protons + 24 neutrons

Does it exist?

mass

rela

tive

abun

danc

e

Fundamental studiesBeyond standard model (neutrino mass, …)

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Properties of radio-nuclidesDifferent neutron-to-proton ratio than stable nuclei leads to: New structure properties New decay modes

=> Nuclear models have problems predicting and even explaining the observations

Example - halo nucleus 11Li: Extended neutron wave functions make 11Li the size of 208Pb When taking away 1 neutron, the other is not bound any more (10Li is not bound)

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EURISOLFuture European RIB facility

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Isotope identification in-flight

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REX post-accelerator

18 May 2009 New opportunities in the physics landscape at CERN 35

REXEBIS

Experiments REXTRAP

MASS SEPARATOR

7-GAP RESONATORS IH RFQ9-GAP

RESONATOR

3.0 MeV/u

2.2 MeV/u 1.2

MeV/u0.3

MeV/u

ISOLDE beam

60 keV

RebuncherPrimarytarget

Optional stripper ISOLDE

LinacLength 11 mFreq. 101MHz (202MHz for the 9GP)Duty cycle 1ms 100Hz (10%)Energy 300keV/u, 1.2-3MeV/uA/q max. 4.5 (2.2MeV/u), 3.5 (3MeV/u)

EBIS • Super conducting solenoid, 2 T• Electron beam < 0.4A 3-6 keV• Breeding time 3 to >200 ms• Total capacity 6·1010 charges• A/q < 4.5

REX-trap• Cooling (10-20 ms)

Buffer gas + RF• (He), Li,...,U• 108 ions/pulse(Space charge effects >105)

Nier-spectrometer• Select the correct A/q and separate the radioactive ions from the residual gases.• A/q resolution ~150

Total efficiency : 1 -10 %

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HIE-ISOLDEQuarter-wave resonators

(Nb sputtered)• SC-linac between 1.2 and 10 MeV/u• 32 SC QWR (20 @ b0=10.3% and 12@ b0=6.3%)

• Energy fully variable; energy spread and bunch length are tunable. Average synchronous phase fs= -20 deg• 2.5<A/q<4.5 limited by the room temperature cavity• 16.02 m length (without matching section)• No ad-hoc longitudinal matching section (incorporated in the lattice)• New beam transfer line to the experimental stations