Lunchtime S.I.E.S.T.A. James Butterworth Finding Atomic Nuclei Offenders with James the Nuclear Detective “It’s element.. element... elementary my dear Watson!”

Setting the Scene

CERN LHC CMS ATLAS ALICE LHCb

ISOLDE

How ISOLDE works – The Primary Target Primary Target 1.4 GeV Protons Exotic Nuclei – Reaction Products  1.4 Gev protons impinge on primary target  Reactions occur  Exotic nuclei are liberated  Reactions: Fission Fragmentation Spallation  1.4 Gev protons impinge on primary target  Reactions occur  Exotic nuclei are liberated  Reactions: Fission Fragmentation Spallation

How ISOLDE works – The Ion Source Ion Source  Ion source ionises atom by knocking out one or more electrons  Ion is now in charge state +q  Types of ion source: Surface Laser Plasma  Ion source ionises atom by knocking out one or more electrons  Ion is now in charge state +q  Types of ion source: Surface Laser Plasma

How ISOLDE works – The Separator  Z = Number of protons  A = Number of protons + number of neutrons  Z = Number of protons  A = Number of protons + number of neutrons  Separates ions according to their A/q ratio  So only ions of the mass we’re interested in get through  Separates ions according to their A/q ratio  So only ions of the mass we’re interested in get through

How ISOLDE works – REX Cooler and Buncher Electron Beam Ion Source Linear Accelerator Electrostatic Accelerating Elements  Ions are trapped, cooled and bunched  Ions are ionised further by EBIS  Ions are accelerated along linear accelerator to experimental station  Ions are trapped, cooled and bunched  Ions are ionised further by EBIS  Ions are accelerated along linear accelerator to experimental station

How ISOLDE works – Miniball Secondary Target γ γ Miniball Detector

What can we learn from these gamma rays?  Nothing – we’re just doing it for fun...  Nuclear structure – a fundamental part of the fabric of the universe  Nuclear astrophysics – how the elements were created  Applications – MRI, nuclear power etc.  Nuclear structure – a fundamental part of the fabric of the universe  Nuclear astrophysics – how the elements were created  Applications – MRI, nuclear power etc.

So why do we need a detective?  Blue Z = 38 (Sr), A = 78, q = +1  Green Z = 37 (Rb), A = 78, q = +1  Blue Z = 38 (Sr), A = 78, q = +1  Green Z = 37 (Rb), A = 78, q = +1  Problem: We get contamination from nuclei with different Z but the same A: isobars  These are our atomic nuclei offenders  Problem: We get contamination from nuclei with different Z but the same A: isobars  These are our atomic nuclei offenders Separator

The scale of the problem

The Solution – The Detector Secondary Target γ γ Miniball Detector The York Bragg Detector

The York Bragg Detector  Gas detector  Consist of six flared modules  The modules sit after the secondary target position and surround the ongoing beamline  Gas detector  Consist of six flared modules  The modules sit after the secondary target position and surround the ongoing beamline

How does a Bragg Detector work?

Where are we now? Simulations Construction

The future...  The York Bragg Detector will be set up and used routinely at Miniball, for nuclear physics experiments  A package of simulations will be available for the users of the detector  The York Bragg Detector will be set up and used routinely at Miniball, for nuclear physics experiments  A package of simulations will be available for the users of the detector

Thank you - Any questions? Sherlock Holmes Silhouette © The Sherlock Holmes Museum, 221b Baker Street, London, England, Used with permission.