Nuclear physics: the ISOLDE facility Magdalena Kowalska CERN, PH-Dept. on behalf of the CERN ISOLDE team Lecture 2: CERN-ISOLDE facility

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 2 Aimed at both physics and non-physics students

Open questions in nuclear physics 3 2 kinds of interacting fermions How to answer the questions: Study nuclei with very different numbers of protons and neutrons (NuPECC long-range plan 2010)

RIB facilities 4 Light beam heavy beam Two main types of (complementary) RIB facilities:  ISOL (Isotope Separation On-Line) and In-Flight RIB: Radioactive Ion Beam Rare Isotope Beam

RIB facilities comparison 5 ISOLIn-Flight Projectilelightheavy Targetthickthin Ion beam energylowhigh Beam intensityhighlow Variety of nuclidessmallerlarge Release from targetslowfast Beam qualitygoodpoor GANIL, GSI, RIKEN, NSCL/MSU

RIB facilities worldwide 6 Existing and in preparation After B. Sherill ISOL-type In-Flight

ISOLDE – short history 7 First beam October 1967 New facility June 1992 Upgrades 1974 and 1988

ISOLDE at CERN 8

ISOLDE within CERN accelerators 9 LINAC2 PSB PS ISOLDE

ISOLDE elements 10 Isotope production via reactions of light beam with thick and heavy target Production – ionization – separation Target Separator

Ion beam intensity Number of extracted ions (yield) is governed by: 11 According to Ulli Koester: primary particle flux x reaction cross section x number of target particles x efficiencies

Production channels 12

Production targets Over 20 target materials and ionizers, depending on beam of interest U, Ta, Zr, Y, Ti, Si, … Target material and transfer tube heated to 1500 – 2000 degrees Operated by robots due to radiation 13 Converter Target Standard Converter Target p+

Inside a standard target 14

Ionization Surface Plasma Lasers 15 After U. Koester

Beam extraction and separation All produced ions are extracted by electrostatic field (up to 60kV) 16 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

Production, ionization, extraction 17 targetTarget+ vacuum+ extraction robots Ion energy: 30-60keV

Separation 18 Magnet separators (General Purpose and High Resolution)

Post-acceleration 19 REX accelerator Ion trapping and cooling Increase in charge state A/q selection Rf acceleration 3MeV*A beam to experiment

Production and selection - example 20 Facility

Example – astatine isotopes 21 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

Extracted nuclides 22 More 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 hall Target stations HRS & GPS Mass-sep. HRS ISCOOL RILIS REX-ISOLDE PS-Booster 1.4 GeV protons 3×10 13 ppp ISOLTRAP CRIS COLLAPS NICOLE MINIBALL and T-REX WITCH Travelling setups Post-accelerated beams 23 Decay spectroscopy Coulomb excitation Transfer reactions Laser spectroscopy Beta-NMR Penning traps Collection points TAS

Facility photos 24

Experimental beamlines 25

HIE-ISOLDE upgrade 26 High Intensity and Energy ISOLDE Works on-going First post-accelerated beam in 2015/2016

ISOLDE physics topics 27 Nuclear Physics Nuclear Decay Spectroscopy and Reactions Structure of Nuclei Exotic Decay Modes Atomic Physics Laser 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 Physics Direct Mass Measurements, Dedicated Decay Studies - WI CKM unitarity tests, search for b-n correlations, right-handed currents Applied Physics Implanted Radioactive Probes, Tailored Isotopes for Diagnosis and Therapy Condensed matter physics and Life sciences

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 28

Reaction probability 29

Reaction probability Primary beam type and energy are important 30

Research with radionuclides 31 Nuclear 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 s-shell p-shell sd-shell fp-shell 34Ne: 10 protons + 24 neutrons Does it exist? mass relative abundance Fundamental studies Beyond standard model (neutrino mass, …)

Properties of radio-nuclides Different 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 32 Example - halo nucleus 11 Li:  Extended neutron wave functions make 11 Li the size of 208 Pb  When taking away 1 neutron, the other is not bound any more (10Li is not bound)

EURISOL Future European RIB facility 33

Isotope identification in-flight 34

REX post-accelerator May 2009 New opportunities in the physics landscape at CERN 35 REXEBIS Experiments REXTRAP MASS SEPARATOR 7-GAP RESONATORS IH RFQ 9-GAP RESONATOR 3.0 MeV/u 2.2 MeV/u 1.2 MeV/u 0.3 MeV/u ISOLDE beam 60 keV Rebuncher Primary target Optional stripper ISOLDE Linac Length11 m Freq.101MHz (202MHz for the 9GP) Duty cycle1ms 100Hz (10%) Energy300keV/u, 1.2-3MeV/u A/q max. 4.5 (2.2MeV/u), 3.5 (3MeV/u) Linac Length11 m Freq.101MHz (202MHz for the 9GP) Duty cycle1ms 100Hz (10%) Energy300keV/u, 1.2-3MeV/u A/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 6·10 10 charges A/q < 4.5 EBIS Super conducting solenoid, 2 T Electron beam < 0.4A 3-6 keV Breeding time 3 to >200 ms Total capacity 6·10 10 charges A/q < 4.5 REX-trap Cooling (10-20 ms) Buffer gas + RF (He), Li,...,U 10 8 ions/pulse (Space charge effects >10 5 ) REX-trap Cooling (10-20 ms) Buffer gas + RF (He), Li,...,U 10 8 ions/pulse (Space charge effects >10 5 ) Nier-spectrometer Select the correct A/q and separate the radioactive ions from the residual gases. A/q resolution ~150 Nier-spectrometer Select the correct A/q and separate the radioactive ions from the residual gases. A/q resolution ~150 Total efficiency : %

HIE-ISOLDE 36 Quarter-wave resonators (Nb sputtered) SC-linac between 1.2 and 10 MeV/u 32 SC QWR  0 =10.3% and  0 =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 m length (without matching section) No ad-hoc longitudinal matching section (incorporated in the lattice) New beam transfer line to the experimental stations