Applications of Stroboscopic detection of synchrotron radiation

1
Applications of Stroboscopic detection of
synchrotron radiation
Inge Serdons
2
Overview
1. Reminder of the principle of stroboscopic
detection 2. Application 1 isomer shift
determination 3. Application 2 long-lived
isotopes 4. Conclusions
3
Overview
1. Reminder of the principle of stroboscopic
detection 2. Application 1 isomer shift
determination 3. Application 2 long-lived
isotopes 4. Conclusions
4
Nuclear Resonant Scatteringtwo identical single
line samples
5
Nuclear Resonant Scatteringtwo identical single
line samples,one with constant velocity
??
w
excited
w
ground
Detector
Counts
Time
6
Nuclear Resonant Scatteringtwo identical single
line samples,one with variable velocity
??
w
excited
w
ground
Detector
Counts
Time
7
Stroboscopic Detection
8
Stroboscopic Detection
9
Stroboscopic Detection
Eu2O3 - Eu2O3
time (ns)
0
3
9
21
24
15
10
Overview
1. Reminder of the principle of stroboscopic
detection 2. Application 1 isomer shift
determination 3. Application 2 long-lived
isotopes 4. Conclusions
11
Isomer shift determinationsome remarks

• To measure isomer shifts with nuclear resonant
  scattering, a reference sample is always needed.
• One always measures the relative isomer shift
  between both samples in the beam, therefore the
  isomer shift of the reference sample should be
  known exactly.
• The aim of this experiment was to confirm the
  validity of the stroboscopic technique for isomer
  shift measurements.

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Isomer shift determinationPressure dependence
of the isomer shift of 151Eu in EuPd2Si2
EuPd2Si2
151Eu

• Fluctuating-valence compound
• In the fast-fluctuations limit ? (1-?) ?2
  ? ?3? probability of finding the Eu-ion in the
  4f6-configuration? isomer-shift?2, ?3 isomer
  shifts of the pure divalent and trivalent ions

Eu structure (Xe) 4f7 5d0 6s2 Eu2 (Xe) 4f7
5d0 6s0 Eu3 (Xe) 4f6 5d0 6s0
13
Isomer shift determinationPressure dependence
of the isomer shift of 151Eu in EuPd2Si2
Eu2 (Xe) 4f7 5d0 6s0
Eu3 (Xe) 4f6 5d0 6s0
DI
Valence fluctuations 7th elektron of Eu2 jumps
back and forth between localized 4f-level and
valence band.
TRI
Energy
0.5 Ry
Fermi-level
14
Isomer shift determinationPressure dependence
of the isomer shift of 151Eu in EuPd2Si2
15
Isomer shift determinationPressure dependence
of the isomer shift of 151Eu in EuPd2Si2
G. Schmiester, B. Perscheid, G. Kaindl and J.
Zukrowski, Valence Instabilities, ed. P. Wachter
and H. Boppart, 1982, 219
16
Overview
1. Reminder of the principle of stroboscopic
detection 2. Application 1 isomer shift
determination 3. Application 2 long-lived
isotopes 4. Conclusions
17
Long-lived Isotopessome remarks

• The stroboscopic technique is not sensitive to
  the lifetime of the isomer.
• We measured 181Ta as an example, the halflife of
  the isotope is 6 ?s. That of the ensemble is of
  the order of 0.5 ?s due to speed-up.
• The aim of this experiment was to confirm the
  validity of the stroboscopic technique for
  measurements with long-lived isotopes.

18
Long-lived Isotopes 181Ta
181Ta
?E 6 214 (2) eV t1/2 6.05 ?s
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Long-lived Isotopes 181Ta
2nd experimental timing-mode
181Ta
?E 6 214 (2) eV t1/2 6.05 ?s
20
Long-lived Isotopes 181TaExperimental setup
1st experiment
Detector
181Ta metal on Mossbauer drive
Si 3 3 3
181Ta metal
21
Long-lived Isotopes 181Ta1st experiment
Two single line samples of 181Ta-metal
150
130
PeriodPP 24 ns
110
90
Counts
70
50
-1
-0.5
0
0.5
1
Velocity (mm/s)
22
Long-lived Isotopes 181TaExperimental setup
2nd experiment
Si 5 1 1
APD
Si 5 1 1
181Ta metal on Mossbauer drive
181Ta metal
Si 3 1 1
23
Long-lived Isotopes 181Ta2nd experiment
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Long-lived Isotopes 181Ta2nd experiment
Two single line samples of 181Ta-metal
25
Overview
1. Reminder of the principle of stroboscopic
detection 2. Application 1 isomer shift
determination 3. Application 2 long-lived
isotopes 4. Conclusions
26
Conclusions

• Isomer shift determination on 151Eu
  determination of change in mean valence of Eu in
  EuPd2Si2
• Measurements on long-lived isotopes like 181Ta
• The stroboscopic method is a valuable asset to
• the hyperfine measurement methods

Future Projects

• Measurement of the first order stroboscopic
  resonance of 181Ta
• Go to other long-lived isotopes like 67Zn

27
Collaborators and Acknowledgements
K.U.Leuven I. SerdonsR. CallensR. CoussementS.
GheysenC. LabbéJ. Odeurs K. Vyvey
Osaka University S. NasuT. OnoS. Morimoto
U.C.Louvain J. Ladrière
JASRI Y. YodaA. Baron Y. YamadaY. Imai
University of Paderborn G. Wortmann