Application of heavy charged particle spectrometry

Application of heavy charged particle spectrometry

1) Identification of superheavy elements by means of alpha decay sequence

2) Study of hot and dense nuclear matter by means of charged particle spectrometry

Table of isotopes in the range of superheavy elementsHeavy ion collision with ultrarelativistic energy

Problem very small cross-sections production only single nuclei ndash necessary unambiguous identification

Energy 1) sufficient for overcoming of Coulomb barrier 2) as small as possible to obtain ldquorelatively stableldquo compound nucleus

Decay of alpha decay sequence rarr alpha particles contain information about energy differences between following nuclei

Production possibilities 1) Neutron capture ndash up to Z = 100 (earlier decay then neutron capture) 2) Reaction of light nucleus on heavy target 3) bdquoColdldquo fusion of heavy nucleus ndash projectile A ~ 40 EEX ~ 10 MeV 4) bdquoHotldquo fusion of heavy nucleus ndash usage of 48Ca (Z = 20) EEX ~ 40 MeV

Production of superheavy elements

Drop model 1) stability decreases with increasing proton number 2) excess of neutrons increases with increasing proton number

Existence of bdquomore stableldquo superheavy elements made possible by existence of magic numbers - shell structure harr shell model

Competition of volume energy (strong nuclear interaction) and coulomb energy

Stability island ndash Z = 114 and N = 184 ndash depends on potential form significant uncertainty

Detection of superheavy elements at GSI Darmstadt

Identification of single cases of superheavy element production and decay

1) Capture of all alpha from decay sequence and determination of their energy2) Identification of fission

ptp

pCM v

mm

mv

Velocity filter

Electric deflectors and dipole magnets

Fel = qE Fmag = qvB

Choice of incurred compound nucleus

Right choice E a B for vCM is FTOT = Fel ndash Fmag = 0

dipole magnets

electric deflectors

TOF

rotatedtarget

quadrupole magnets

Stopping of beam

svazek

SHIP device

Elements 107 ndash 112 device SHIP at GSI Darmstadt fusion reaction on Pb Bi nuclei usage of separation separation of compound nucleus implantation to active volume of detector and identification by means of alpha decay sequences

Rotated target (Pb Bi) low thaw pointintensive beam ndash 1012 nucleis

TOF spectrometer

Suppression of residual background

Start ndash transition detectors thin carbon foils (electron production) and mikrochannel plates

Stop ndash 16 silicon strip detectors ΔE = 14 keV for alpha from 241Am

Efficiency 998 resolution 700 ps

Coverage 80 of 2π

HPGe detectors ndash photons from deexcitation of excited nuclei

transition detectory

stop detector(silicon)

Cross sections až ~ pb single nucleus per tens days

Very intensive beams during many months

107 Bh Bohrium108 Hs Hassium109 Mt Meitnerium110 Dm Darmstadtiumu111 Rg Roentgenium112 Cp Copernicium

Fusion per low energies

Results from GSI confirmed also by Japanese laboratory RIKEN

First identified decays of named element with present second highest Z

Further ndash fusion by means of higher energies

(112 113 114 115 116 117 118)Problem ndash sequence ends by unknown isotopes rather long decay time (problem with identification by means of coincidences) Year 2006 ndash join ndash looks OK

Reaction 48Ca + 244Pu rarr Z = 114 A = 292

Excitation function for C+Pu reaction

Map of superheavy elements

Cold fusion

Hot fusion Stability island

Neutron number

Pro

ton

nu

mb

er

108 Hassium ndash one from last element chemically studied

Oxid of ruthenium RuO4

Oxid of osmium OsO4

Oxid of hassium HsO4

Chemical analysis of single atoms

Nucleus decays early than new is produced

Study of volatility rarr oxides of VIII group are very volatile

Known isotopes of hassium

First produced hassium nucleus

Production of more stable Hs isotopes

Narrow channel with decreasing temperature from -20oC up to -170oC rarr the more volatile the further molecules will flight before adsorption

Hs with A ~ 288 will be maybe very stable

Nucleon Decaynumber halftime

only elements in this column can be octavalent

Element density [gcm3] melting point [oC] boiling point [oC] stiffness [Mohs]

Study of hot and dense nuclear matter by means of charged particles production

Effort to build 4π detectors of charged particles

Example of FOPI spectrometer at GSI Darmstadt

Determination of nuclear matter temperature ndash spectrum

Scheme of FOPI spectrometer

Display of event detected by FOPI spectrometer

Spectrometer of charged particles FOPI

Relativistic heavy ion collisionsrarrBig number of produced charged particles

Determination of pressure ndash particle collective flow

Determination of nuclear matterequation of state

2y

2x

2222T ppcmcm Introduction of transfer mass mT

and rapidity y

z

z

pcE

pcE

ln2

1y and then

cos1

cos1ln

2

1

cosmvmc

cosmvmcln

2

1y

Target region YREL -1 Collision region YREL 0 Projectile region YREL +1

Relative rapidity YREL = (Y - YPRO2)(YPRO2) YPROJ ndash projectile rapidity

Identification of charged particlesSpectra of charged particles (Ni+Ni a Au+Au experiments with beam energy 1 GeVA)

Two Arm Photon Spectrometer

Detection of gamma neutrons and charged particles

384 BaF2 detectorswith plastic veto ndash distinguishing of neutral and charged particles

cooperation with TOF plastic wall

- collision characteristic

Beam energy 10 MeV - 200 GeV (GSI Darmstadt KVI GroningenGANIL Caen CERN)

Collective flow of nucleons

N = N0( 1 + Amiddotcosφ + Bmiddotcos(2middotφ))

Relative rapidity YREL = (Y - YPRO2)(YPRO2) YPROJ ndash projectile rapidity

Target region YREL -1 Collision region YREL 0 Projectile region YREL +1

A ndash magnitude of asymmetry in the collision plane B ndash magnitude of asymmetry perpendicular to it (eliptical flow)

A lt 0 B = 0 A = 0 B lt 0 A gt 0 B = 0

Bounce off particles to the Reaction plane

Squeeze out of particles perpendicular to reaction plane

Experimental data ndash dependency of collective flow on nucleons number ndash agreement of hydrodynamical models

Dependence of collective flows on rapidity (origin of nukleons)

Target region Collision region Target region Projectile region

Application at material research - scattering channeling ion reaction

Tandetrom 4130 MC at NPI ASCR is used for material research ndash from H up to Au energies from hundreds keV up to tens MeV

Usage ions for modification and studies of structure of surface layers of solid materials

Different types of silicon semiconductor detectors of charged particles

Usage of ion accelerators for relatively low energies in the range from keV up to MeV

Spectrometers of charged nuclei ndash often semiconductor silicon detectors

RBS (Rutheford Backscattering Spectroscopy) - spectrometry of charged pasrticles back scattered by Rutheford scattering ndash layers from nm up to μm ndash spectrometry of scattered ions by semiconductor detectors Change of energy given by momentum change and ionisation losses ndash profiles of impurities distribution materials are determined ndash mainly heavy nuclei

RBS channeling ndash channeling of charged particles ndash crystal structures ndash determination of distinctive directions of crystal axes and impurities ndash slight turning of crystal sample

ERDA (Elastic Recoil Detection Analysis) ndash detection of atoms knocked on by ions ndash mostly lighter nuclei from hydrogen up to nitrogen ndash possibility of control changes of surface properties ndash study of hydrogen amount at polymers ndash connection with measurement of ion time of flight

ERDA

incident ion

scattered ion

detector

RBS

Elastic scattering ions

incident ion

reflected ion

detector

Ion reaction with nucleiPIGE (Particle Induced Gamma ray Emission)

PIXE ndash (Particle Induced Gamma ray Emission)

Ion litography and ion beam machining ndash preparing of microelectronical a optoelectronical components and microscopic mechanical devices

Sprockets produced by ion litography method at photoresistive material

Ion implantation ndash modification of surface material layers

Material modification and working

AMS ndash accelerator mass spectroscopy ndash impurity of elements with concentration 10-15 ndash often for carbon dating

Ion microprobe ndash very narrow and intensive ion beam ndash usage ndash scanning of object surface with micrometer accuracy

see gamma spectroscopy