Portuguese groups at ISOLDE - CERN
Ulrich Wahl
Instituto Tecnológico e Nuclear (ITN) Sacavém
Centro de Física Nuclear da Universidade de Lisboa (CFNUL)
ISOLDE and Nuclear Solid State Physics
Portuguese experiments at ISOLDE:
history, people, collaborations
Examples:
- position-sensitive electron detector development
- emission channeling lattice location of Fe in Si
- PAC investigation of O and F in High-Tc Hg-1201
Conclusions amd outlook
The ISOLDE on-line isotope separator
Available beams:
~ 600 isotopes of
~ 70 elements
+
surface
ionization
-
Li Be
mass
separation
target and
ion source
Na Mg
laser
selective
ionization
Hot
plasma
discharge
Cold
He
B C N O F Ne
Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
60 keV
acceleration 1 GeV
protons
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Th Pa U Np Pu AmCm Bk Cf Es FmMd No Lr
radioactive ion beams
Experiments involving Portuguese groups:
typically around 10-12 shifts per year
i.e. ~3% of ISOLDE availability
Solid State Physics
22%
Particle and
Astro-Physics
13%
ISOLDE
Experiments
2003
Biology/Medicine
5%
Atomic Physics
15%
Weak Interaction and
Nuclear Physics
46%
37 Experiments
300 Users
96 Institutes
22 Countries
375 8h-shifts
of radioactive
beams
Semiconductor Spectroscopy
sensitive to chemical nature
or electronic properties
(some require radioactive istopes
)
1020
1020
EXAFS
Channel.
1018
NMR
1016
1016
ENDOR
1014
1014
Hall
EPR
1012
EC
DLTS
10
10
108
PL
PAC,ME
Portuguese groups:
emission channeling (EC)
perturbed angular correlation (PAC)
NMR-ON
1012
1010
defect concentration (cm-3)
1018
108
-NMR
106
106
Experimental techniques used with radioactive isotopes at ISOLDE
History of e--g PAC and EC at ISOLDE-CERN
1986
e-g PAC at ISOLDE
1994
Test of new PAC probes IS-P66
IS01/13
spokesperson J.C.Soares
e--g PAC
spokesperson J.G. Correia
197mHg, 73Ge, 127Cs,
80Br
1997
~2006
IS360 Studies of high-Tc superconductors with radioactive isotopes
1998
~2006
IS368 Lattice location of transition metals and rare earths in semiconductors
2000
~2005
IS390 Studies of colossal magnetoresistive oxides with radioactive isotopes
2001
New improved electron emission channeling pad detectors and
spokesperson J.G. Correia (ITN & CFNUL)
spokesperson U. Wahl (ITN & CFNUL, then IKS Leuven)
spokesperson V. Amaral (U Aveiro)
development of self-triggering front-end electronics
Cooperation agreement between ITN, CFNUL and CERN EP-ATT Group (now: PH-TA1)
Network of groups involved
KU Leuven
(Belgium)
Prof. André Vantomme
2 PhD students:
Bart De Vries
LEUVEN
Stefan Decoster
Univ. of Kwazulu Natal
(South Africa)
Prof. Krish Bharuth-Ram
University of Göttingen
(Germany)
Prof. Hans Hofsäss
(future collaboration)
CFNUL Lisbon
ITN Sacavém
Prof. José C. Soares Dr. J. Guilherme Correia
Prof. Manuel. R. Silva
Dr. Ulrich Wahl
2 PhD students:
Dr. Heinz Haas (retired)
Elisabete Rita
Ana C. Marques
1 Diploma student:
Sonia Dias
University of Porto
University of Aveiro
Prof. Vitor Amaral
Dr. Mario S. Reis
1 PhD student:
Armandina Lopes
1 Diploma student:
João C. Amaral
Prof. J. Pedro Araújo
1 Masters student:
Tania Mendonça
CERN
Dr. Peter Weilhammer
(detector development)
Funding: mainly from national sources
KU Leuven
(Belgium)
Fund for Scientific
Research - Flanders
(dedicated project
on emission channeling)
CFNUL Lisbon
ITN Sacavém
Portuguese Foundation for Science & Technology
(dedicated CERN project on PAC & emission channeling)
University of Porto
Univ. of Kwazulu Natal
(South Africa)
University of Aveiro
University of Göttingen
(Germany)
Federal Ministry of
Education and Research
(dedicated project
on emission channeling)
Portuguese Foundation
for Science & Technology
(dedicated CERN project on
magnetic oxides)
CERN
Position-sensitive Si pad detectors for Emission Channeling
Collaboration:
ITN, CFNUL
& CERN PH-TA1 group
Future detectors:
pads self-triggering
 5 keV trigger
 10 kHz readout
73As
in ZnO
low electron energy
300
[-1102]
42 keV
noise
100
0
­+ M2: - M2 :
­
- z:¬
- z:
-10
-5
0
5
52 keV
10 20 30 40 50 60 70 80
energy [keV]
-10
10
-5
-5
0
0
5
5
10
10
+ z:
+ z:
¯
¯
2
+ M 1: ¬
1
0
-1
rel. M 1-angle [deg]
-2
- M 1: ®
+ M2: - M2 :
¬
®
cn-10
te rclw clo ckw
rel. Z-c oordinate [m m ]
counts
200
Cooled
2oC
ROI
"on-line" display: template C:\ORIGIN\PADSPEC4.OTP read with script file C:\ORIGIN\CHANRED4.SCR
"on-line" display: template C:\ORIGIN\PADSPEC4.OTP read with script file C:\ORIGIN\CHANRED4.SCR
2
1
0
-1
-2
2
1
0
-1
-2
rel. Z-c oordinate [m m ]
12 keV
0
[0001]
Co nve rsion elect ron em issio n ch an ne lin g with 30 mm x 30 mm Si p adCo
4 dnve
etersion
cto r: elect ron em issio n ch an ne lin g with 30 mm x 30 mm Si p ad 4 d ete cto r:
-10
3.37E 3 -- 3.45E3
3.29E 3 -- 3.37E3
3.21E 3 -- 3.29E3
3.12E 3 -- 3.21E3
3.04E 3 -- 3.12E3
2.96E 3 -- 3.04E3
2.88E 3 -- 2.96E3
2.8E 3 -- 2.88E3
-5
0
5
+ Mfro1:m ¬
rel.
it is viewn
t he det ecto
r
Arsenic
occupies
multiple sites
in ZnO
3.85E 3 -- 4E3
3.7E 3 -- 3.85E3
3.55E 3 -- 3.7E3
3.4E 3 -- 3.55E3
3.25E 3 -- 3.4E3
3.1E 3 -- 3.25E3
2.95E 3 -- 3.1E3
2.8E 3 -- 2.95E3
10
c ounts raw data
c ounts raw data
2
1
the plo t sh ows
th e crystal
as
®
cn te rclw clo ckw
0
-1
M 1-angle [deg]
-2
- M 1: ®
the plo t sh ows th e crystal a s
it is viewn fro m t he det ecto r
Lattice site changes of implanted 59Fe in Si
simulation best fit
experiment
-2
-1
0
1
2
-2
-1
0
1
2
-2
experiment
simulation best fit
-1
-2
0
1
2
-1
0
1
2
<111>
2
1.23 - 1.27
1.19 - 1.23
1.15 - 1.19
1.11 - 1.15
1.07 - 1.11
1.03 - 1.07
0.99 - 1.03
0.95 - 0.99
1
0
-1
-2
<100>
2
1.18 - 1.21
1.15 - 1.18
1.12 - 1.15
1.09 - 1.12
1.05 - 1.09
1.02 - 1.05
0.99 - 1.02
0.96 - 0.99
1
0
-1
-2
<110>
2
1.10 - 1.12
1.08 - 1.10
1.06 - 1.08
1.05 - 1.06
1.03 - 1.05
1.01 - 1.03
0.99 - 1.01
0.97 - 0.99
1
0
-1
-2
<211>
2
1.15 - 1.18
1.12 - 1.15
1.10 - 1.12
1.07 - 1.10
1.04 - 1.07
1.01 - 1.04
0.99 - 1.01
0.96 - 0.99
1
0
-1
-2
-2
-1
0
1
2
-2
-1
0
1
2 [deg]
-2
<111>
1
1.56 - 1.66
1.46 - 1.56
1.37 - 1.46
1.27 - 1.37
1.17 - 1.27
1.08 - 1.17
0.98 - 1.08
0.88 - 0.98
0
-1
-2
<100>
2
1.41 - 1.48
1.34 - 1.41
1.27 - 1.34
1.21 - 1.27
1.14 - 1.21
1.07 - 1.14
1.00 - 1.07
0.93 - 1.00
1
0
-1
-2
<110>
2
1.10 - 1.13
1.08 - 1.10
1.05 - 1.08
1.02 - 1.05
0.99 - 1.02
0.97 - 0.99
0.94 - 0.97
0.91 - 0.94
1
0
-1
-2
<211>
2
1.14 - 1.18
1.11 - 1.14
1.07 - 1.11
1.04 - 1.07
1.00 - 1.04
0.97 - 1.00
0.94 - 0.97
0.90 - 0.94
1
0
-1
-2
-2
-1
0
1
2
-2
-1
0
1
2 [deg]
experiment
simulation best fit
-1
-2
0
1
2
-1
0
1
2
<111>
2
1.84 - 1.97
1.71 - 1.84
1.57 - 1.71
1.44 - 1.57
1.31 - 1.44
1.18 - 1.31
1.04 - 1.18
0.91 - 1.04
1
0
-1
-2
<100>
2
1.53 - 1.62
1.45 - 1.53
1.36 - 1.45
1.27 - 1.36
1.18 - 1.27
1.10 - 1.18
1.01 - 1.10
0.92 - 1.01
1
0
-1
-2
<110>
2
1.47 - 1.55
1.40 - 1.47
1.32 - 1.40
1.25 - 1.32
1.17 - 1.25
1.10 - 1.17
1.02 - 1.10
0.95 - 1.02
1
0
-1
-2
<211>
2
1.35 - 1.41
1.29 - 1.35
1.24 - 1.29
1.18 - 1.24
1.12 - 1.18
1.06 - 1.12
1.01 - 1.06
0.95 - 1.01
1
0
-1
-2
-2
-1
0
1
2
-2
-1
0
1
2 [deg]
as-implanted:
annealed at T=300°C:
annealed at T=800°C:
mainly displaced
substitutional Fe
mainly tetrahedral
interstitial Fe
mainly ideal
substitutional Fe
Fe is gettered by at least two types of vacancy-like defects
Following release to interstitial state re-gettering occurs at a different
gettering center on ideal substitutional sites
U. Wahl et al., accepted by Phys. Rev. B
Oxygen & Fluorine Configurations in Hg1201 (High-Tc)
 ~ 0.20
Experiment
Ii
I
g
EFG Simulations
100
1
Q 
g
If
50
g
start
clock

Hg
stop
O(2)
0
0
Cu
time
O(1)
2500
(Mrad/s)
5000
0.34 (a)
 ~ 0.0
Ba
 Q.Vzz

100
frequency
50
Electric Field Gradient

dopant configuration
fingerprint
HgBa2CuO4+
d
Tc > 92K
0
0
2500
5000
(Mrad/s)
J.G. Correia et al., submited to Phys. Rev. B
Conclusions and outlook:
Currently and near future (till ~2006):
 IS368: Lattice location in semiconductors, e.g.
Si, Ge, SiGe, diamond,
III-V, nitrides, II-VI, ZnO…
electrical doping, transition metals,
rare earths,
diluted magnetic semiconductors
 IS360: PAC in High-Tc superconductors
 IS390: Magnetism in manganites (CMR)
After 2006: New emission channeling proposal(s) applying…
 new position-sensitive detectors (self-triggering pad, CCD)

- on-line experiments with short-lived isotopes
- low energy electron emitters (Auger electrons?)
a new variety of elements (e.g. Mg, Co, Ni, Zn, Ge)
will be available for emission channeling