Anastasios LagoyannisTandem Accelerator Laboratory

Institute of Nuclear and Particle PhysicsN.C.S.R. “Demokritos”

Current and Future projects at the

TANDEM accelerator

Tandem Layoutμ

-PIX

E

RBS , NRA, ERDA …Charged-particle induced X rays

Auger Spectrom.

Ato

mic

ph

ys

ics

multipurpose

scattering chamber4 HPGe detect. array

γ - spectrometry charged-part. irradiations

d-filled gas-cell

TritiatedTi-target(rotating)

ne

utr

on

irr

adia

tio

ns

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17

γ - calorimetry

Nuclear Astrophysics

p-processNetwork of more than 20000 reactions

(,n), (,p), (,), n-, p-, -captures,

-decays, e-captures

a huge number of cross sections

have to be known

n captures

p captures

α capturesM. A

rno

uld

an

d S

. Go

riel

y P

hys

. Rep

. 38

4, 1

(2

00

3)

HAUSER-FESHBACH THEORY

r := <>max. / <>min.

for 14 different sets of nuclear ingredients

(OMP, NLD, …) in HF calculations.

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17

Experimental Methods

A. LagoyannisInstitute of Nuclear and Particle PhysicsNCSR “Demokritos”

HPGe (ε =100%)

15o

BGO Mask

Angular Distribution

discreteexcited

states

ground state

unresolvedexcited states

Compound Nucleus

Target Nucleus

+ p

roje

cti

le

Q-value

+ E

pro

jentry state

primaries

γ0

γ1

γ2

γ3

...

W()=A0(1+a2P2(cos)+ a4P4(cos))

j

j

pA

ANN

A,0

Angular distribution for γ0,γ1,…

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17

The 4π γ-summing method

0 2000 4000 6000 8000 10000 12000

103

104

105

106

Co

un

ts /

mC

E (keV)

α + 92Μο

beam-induced bgd

sum

pea

k

Solutions (up to now):

• Theoretical calculations

• Simulation

No “real” experimental solution

=(Y/)*(1/)*(A/NA)

BUT

=ƒ(E,M)

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17

Efficiency Calculation

pos. apos. b pos. c

in/out ratios:

M=1 R = 2

M=2 R = 2 × 2 = 4

M=3 R = 2 × 2 × 2 = 8

M=4 R = 2 × 2 × 2 × 2 = 16

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17

BGO Ball

80 BGO crystals

• Thickness = 6.5 cm

• ΩBGO

~80%

• ε ~ 95% @ 1000 keV

• εtot

~ 70% @ 1000 keV

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17

Ion Beam Analysis Techniques

Ion Beam Analysis (IBA) is based on the

interaction of a high-energy charged

particle with the electrons and the nuclei of

the material atoms.

This interaction can lead to the emission of

particles or radiation the energy of which

is characteristic of the elements that

constitute the sample material.

Method Interaction Ideal for

Backscattering Spectrometry

(RBS/EBS)Elastic scattering at backward angles

Depth profiling of heavy elements in

light or medium-Z matrices

Elastic Recoil Detection

Analysis (ERDA)Elastic recoil at forward angles Depth profiling of light elements

Nuclear Reaction Analysis

(NRA)

Nuclear reaction between beam and target

nuclei, producing a light charged particle

Depth profiling of light elements in

high- or medium-Z matrices

Particle-Induced Gamma–ray

Emission (PIGE)

Prompt γ-ray emission during ion beam

irradiation

Bulk analysis of light elements from

hydrogen to silicon

Particle-Induced X-ray

Emission (PIXE)

Characteristic X-ray emission following

ionization by the primary beamBulk analysis of elements with Z>11

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17

Differential Cross Section Measurement

Differential cross sections for EBS - RBS

natMg(d,d0)natMg

Ed,lab = 1660 – 1990 keV

Angles = 90o to 170o

N. Patronis et al, Nucl. Instr. and Meth. B 337 (2014), 97.

Motor driven goniometer

Great angular accuracy (0.01 deg.)

Up to 4 targets

Water cooling available

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17

10B(p,p’γ)10B

Differential Cross Section Measurement

• Electronically controlled turntable

• Initial angles: 0o – 55o – 90o ‐ 165o

• 4 HPGe detectors (1 – 80%, 3 – 100%)

placed between 25 and 30 cm from target

• Air cooled target

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17

Benchmarking

• Acquisition of thick target spectra to different beam energies and angles

• Different thick target matrices (channeling - stopping power effects)

• Simulation of the spectra with the existing cross sections

• Theoretical calculations R - matrix (if possible)

V. Paneta et al, Nucl. Instr. and Meth. B 318 (2014), 1

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17

NRA Example

Plasma Facing Components on JET/Tokamak

Study of the erosion, deposition, materials

migration and fuel retention in fusion plasma

devices.

Understanding the mechanisms

predict the lifetime of wall components & assess

the amount of fuel retained in the machine

Depth profiling of D, Be, C, N, O

NRA with a deuteron at Ed= 1.7 MeV.

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17

Elastic Recoil Detection Analysis

Heavy ions are used as the ion beam

Suitable for the detection of

light elements (Z<17) on heavy substrates

Used for H, D, He depth profiling

Detection of the light nuclei at

forward angles

In simple ERDA experiments necessary to

use filters in front of the detector in order to

stop the heavy beam ions

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17

Time Of Flight ERDA

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17

Micro beam

Ancient spoon found in Mykines, Greece

Beam spot is reduced to μm

micro-structural elemental analysis

Elemental mapping capability

Small samples analysis

Low beam currents

time consuming

Au Ca

O Si

Zn Cu

Ag Mo

External Beam Setup

A. LagoyannisI.N.P.P. MeetingWednesday 15/11/17