Transcript Highlights from ISOLDE

Fluorescence detection in a Penning trap
Radu Cazan
Helmholtzzentrum für
Schwerionenforschung
First peak – from where?
800000
-> laser scanned in 100 sec over 2 GHz
Fluorescence rate (cps)
700000
600000
500000
400000
~50 MHz
300000
26Mg+:
200000
~3 GHz to the right!
?
100000
0
-500
-400
-300
-200
-100
0
Laser detunning (MHz)
100
200
The beamline & the trap
Channel
Photomultiplier
Injection of externally produced ions
• dynamic ion capture cycle
• low energy and TOF allow
selection of captured ions
Option with a cooling mechanism:
Stacking of successive ion
bunches
•No2 detectable
ms gate
fluorescence for
•hot
upions
to 5 –Hz
the ones which are
•most
almost
no ion in
loss
probably
the middle!
Cooling the axial motion
Maintain the laser redshifted for a cold ion and leave the axial motion
do the job:
Isat=2.5 mW/mm2
ωz
Cooling time for
100 eV ions: ~1 s.
ωz
Fluorescence and line profile
800000
-> laser scanned in 100 sec over 2 GHz
100 K
1.57 GHz
10 K
496 MHz
600000
1K
157 MHz
500000
Natural
linewidth
43 MHz
400000
1 mK
(ħΓ/2kB)
2 MHz
Fluorescence rate (cps)
700000
300000
~50 MHz
=> T~0.1 K
=> T<<0.1 K
200000
100000
0
-500
-400
-300
-200
-100
0
Laser detunning (MHz)
100
200
800000
700000
600000
Fluorescence rate (cps)
500000
400000
300000
200000
100000
0
500000
1072024,8
1072025,2
1072025,6
1072024,8
1072025,2
1072025,6
400000
300000
200000
100000
0
Frequency (GHz)
Zeeman shift
Zeeman shift: 13.996 GHz/Tesla
Fluorescence vs. polarization
-
800000
600000
400000
Fluorescence rate (cps)
200000
0
800000 -1500
-1000
-500
0
-1000
-500
0
-1000
-500
0
600000

500
+
500
400000
200000
0
800000 -1500
600000
400000
200000
0
-1500
Laser detunning (MHz)
500
Quantized fluorescence jumps
2 ions
2000
1600
1200
800
Fluorescence rate (cps)
400
0
-1500
2000
-1000
-500
0
-1000
-500
0
-1000
-500
0
3 ions
500
1600
1200
800
400
0
-1500
2000
4 ions
500
1600
1200
800
400
0
-1500
Laser detunning (MHz)
500
1600
Y=A+B*X
Parameter
Value
Error
-----------------------------------------------------------A
26,97901
19,53865
B
144,48816
3,62167
------------------------------------------------------------
1400
Detected photons
1200
1000
800
600
400
~145 photons per ion per cooling cycle
~ 300 cps fluorescence rate per trapped ion
200
0
0
1
2
3
4
5
6
Trapped ions
7
8
9
10
11
Estimation of the trapped ion number
800000
Fluorescence rate (cps)
700000
600000
500000
400000
-> laser scanned in 100 sec over 1 GHz
~ 145 photons per ion per cooling cycle
~ 300 cps fluorescence rate per ion
Height=728.000 cps
=> ~2400 ions
Area=1.950.000 photons
=> up to 13.500 ions
~50 MHz
300000
200000
100000
0
-500
-400
-300
-200
-100
0
Laser detunning (MHz)
100
200
Laser system for cooling of Mg+
P ≈ 500 mW
P ≈ 950 mW
= 1118 nm
 = 559 nm
P ≈ 320 mW
 = 279 nm
P ≈ 17 mW
P ≈ 4 mW
P ≈ 200 mW
P ≈ 100 mW
Further planned measurements
 [nm]
A [1/s]
- 2P3/2
710.17
24
40Ar13+
2P
2
1/2 - P3/2
441.24
104
40Ca14+
3P - 3P
0
1
569.44
95
207Pb81+
F=0 - F=1
1019.7
20
209Bi82+
F=4 - F=5
243.9
2849
209Bi80+
F=4 - F=5
1555
12
Type
Ion
low q
207Pb+
2P1/2
B-like
C-like
H-like
Li-like
Transition
final accuracy limited by the Doppler broadening
Dn D
8k BT ln 2
• with resistive cooling Dn/n0 ≈ 10-6 to 10-7

2
-7
-8
n
mc
• with sympathetic cooling Dn/n0 ≈ 10 to 10
0
Type
Ion
low q
207Pb+
Transition
2P1/2
- 2P3/2
 [nm]
A [1/s]
710.17
24
Verdi V18 pumped Ti:Sa Laser, 700-1100 nm, ~1 W output with 10 W of 532 nm
Type
Ion
C-like
40Ca14+
Transition
 [nm]
A [1/s]
3P - 3P
0
1
569.44
95
Verdi V18 pumped Coherent 699 Dye Laser, >0.5 W output with 9 W of 532 nm
view of the trap and the magnet