the ion trap facility shiptrap at gsi status and perspectives michael block for the shiptrap...
TRANSCRIPT
The ion trap facility SHIPTRAP at GSI
Status and Perspectives
Michael Block for the SHIPTRAP collaboration
Outline
• Introduction• SHIPTRAP layout• Stopping cell efficiency measurements• Penning trap performance• Perspectives for mass measurements• Summary• Outlook – FT-ICR
targetwheel
primary beam @ a few MeV/u
fusion products @ a few 100 keV/u
detector
8
8
20
20
50
50
126
82
82
28
28
• mass measurements • laser spectroscopy• ion chemical reaction studies• in-trap decay experiments
100Sn
SHE
SHIP
SHIPTRAP physics program:
precision measurements with heavy ions produced at SHIP:
SHE half-lives
G. Audi et al. / Nuclear Physics A 729 (2003) 3–128
Above Fm (Z=100) more than90 nuclides have a half-life > 100ms
suitable for trap experiments
Fm
SHE mass precision
G. Audi et al. / Nuclear Physics A 729 (2003) 3–128
only very few masses knownfrom decay chains
Z=112
N=
16
8
Purification Trap
Measurement Trap
Detector Downstream Experiments
ExtractionRFQ
StoppingCell
fusion productsfrom SHIP
Buncher
1 2
3
4
56
The SHIPTRAP set-up
•Stopping
•Cooling
•Accumulation
•Purification
•Measurement
SHIPTRAP SHIPTRAP stopping cellstopping cell
LMUMünchen
PhD thesis J. Neumayr
to buncher
SHIP beam
Lens Lens
Primary Beam
Ge-Detector C-Foil
Target Cup
Cup
Cell
RFQ
Movable Si-Detector(+ movable -source)
Dipole(B
max = 0.84 Tm)
Si-Detector
Quarz Monitor
Efficiency measurementswith longitudinal extraction:
Reaction: 121Sb(35Cl,4n)152Er
152Er: T1/2=10.3s, E=4.8 MeV
Test beam line at MLL-Garching
Target: 260 µg/cm²Primary beam energy : 150 MeVBeam intensity: ~ 4.5x109 s-1Recoil energy: 28.4 MeVEntrance window:Ti 4 µm / 1.8 mg/cm²
efficiency for longitudinal extraction tot = 8.4 % ± 1.5 %
0 10 20 30 40 50 60
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Ab
solu
te E
ffic
ien
cy [
%]
IAg / (107 / s)
70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220
10
100
1000
10000
Ag(H2O)
2
+
Co
un
tsMass / u
Ag+
Kr+
Ag(H2O)+
Hg+
Xe+10 mbar
- 5
10 mbar- 7
to CF D/T DC
RF Q uadrupole
( Ion Linear RF Trap)Guide /
DC Q uadrupoleEinzel Lens
Ac celerator
Electrostatic
Double-Stage
Reflector
MC P Detector
10 mbar- 2
From Gas Cell
Efficiency measurements with
the Ortho-TOF mass spectrometer
PhD thesis S. Eliseev
Stopping cell and extraction RFQ efficiency for atomic ions:
tot = 4.0 % ± 1.0 %
Munich beam time 08/2003
Primary beam:
107Ag @ 23MeV
mass resolving power up to 20,000
efficiency 1-3%
vacuum problem
Stopping and extraction efficiencyfor perpendicular extraction
4.8% efficiency 2.7% efficiency
ExtractionRFQ
StoppingCell
fusion productsfrom SHIP
Buncher
SiliconDetector
SiliconDetector
3500 3750 4000 4250 4500 4750 5000 5250 5500 5750 60000
100
200
300
400
500
600
700
800
900
1000
//
Co
un
ts /
[17
keV
]
E [keV]
-spectrum behind extraction RFQ
152Ho
152Er
153Er
GSI beam time 11/2003
Reaction:116Sn(40Ar,4n)152Er
Target: 440 µg/cm²Primary beam energy : 4.2 MeV/uEntrance window: Ti 4 µm
1.8 mg/cm²
stopping cell efficiency measurements
test ion efficiency extraction fields
DC / funnel
extraction
MLL 152Er
-emitter
8.4 % ± 1.5 % 10 V/cm 10 V/cm 0o
GSI 152Er
-emitter
4.8 % ± 0.7 % 10 V/cm 5 V/cm 90o
MLL 107Ag+
atomic ions
4.0 % ± 1.0 % 5 V/cm 10 V/cm 0o
RF
RF
+
-
trapping
ion beam
extraction
stoppingcell
z
UDC
ion bunch
He buffer gas
Penningtraps
r0
Performance of the RFQ Buncher
•efficiency: in transmission mode: 95 % in bunched mode: 40 %
•cooling time: ~3 ms•emittance (2.5 keV):
longitudinal: 5 eV µs transversal: 20 mm mrad
0 25 50 75 100 125 1500
20
40
60
80
100
Num
ber
ofbu
nch e
dio n
s
Time of flight [ s ]
Storage time = 5.6 ms
PhD thesis: D. Rodríguez M. Mukherjee
SHIPTRAP Penning trap system
purification trap measurement trap
PhD thesis: G. Sikler, S. Rahamanconstructed in collaboration with JyväskyläIn the framework of EXOTRAPS
8-fold segmented ring electrode
8-fold segmented ring electrodecorrection electrodescorrection electrodes
809526 809527 809528 809529 809530110
115
120
125
130
135
140
145
150
Me
an
TO
F [
s]
Excitation Frequency [Hz]
m/m = 860,000
133Cs
excitation time 1.2sFWHM = 0.95 HzTOF Eff. = 21%
Penning trap performance
mass resolving power > 80,000
for 133Cs (total cycle 400ms)
purification trap measurement trap
mass resolving power > 850,000
for 133Cs
End capCorrectio n electrodes
Ring electrode Ring
electrodeCorrection electrodes
Correction electrode
Correction electrode
End cap End capEnd cap
50 mm
32 mm 3 mm
Purification trap
Diaphragm
Measurement trap
Ion bunch
809680 809700 809720 809740 8097600
20
40
60
80
100
120
140
160
180
200
=10 Hz
Cts
Cyclotron Frequency [Hz]
133Cs
excitation time 200ms
Purification Trap
Measurement Trap
Detector
ExtractionRFQ
StoppingCell
fusion productsfrom SHIP
Buncher
1 2
3
4
56
SHIPTRAP - Current Performance
~1% efficiency
4.8% efficiency~ 5ms extraction time
access to nuclei with:• production cross section ~ 1b• half-life > 100ms
expected precision ~ 10-7 - 10-8
m/m > 860,000~ 1s cycle time
m/m > 80,000~400ms cycle time
2.7% efficiency~ 3ms cooling time
taken from S. Hofmann and G. Muenzenberg,Rev. Mod. Phys., Vol. 72, No. 3, July 2000
Perspectives on direct mass measurements of SHE
crosssection
overallefficienc
y
required beam time
10 b 1 % ~ 0.28h
10 % ~ 0.03h
1 b 1 % ~ 2.8 h
10 % ~ 0.28 h
100 nb 1 % ~ 28 h
10 % ~ 2.8 h
10 nb 1 % ~ 11.5 d
10 % ~ 28 h
for a precision of 10-7 using the TOF method
First mass measurements in the region A=150
G. Audi et al. / Nuclear Physics A 729 (2003) 3–128
The numbers give the mass precision in keV
half-lives
Calculated yields for Lu isotopes and A=157 isobars at SHIP
Reactions: 58Ni + 102Pd 157X + xnyp 58Ni + 96Ru A-x-1Lu + pxn
T1/2: 46ms 80.6ms 650ms 900ms 6.8s 115ms 10.1ms
Summary
• Stopping cell efficiency 5%, extraction time ~ 5ms• RFQ buncher: 40% efficiency, ~ 1ms cooling time• Purification trap: mass resolving power > 80,000• Measurement trap: mass resolving power >
860,000
All individual components operational and characterized:
Gas cell and extraction RFQ successfully operated in beam times at GSI and MLL:
• Overall efficiency of the stopping cell and extraction RFQ 5%• Overall efficiency including the RFQ buncher 2.7%
First mass measurements can be performed in 2004
Outlook (I) - Improving the efficiency
• investigate loss mechanisms inside the gas cell• reduce neutralization and molecule formation by impurities • use higher buffer gas pressure and thinner entrance windows• higher extraction fields (e.g. different funnel) • change from 90 degree to longitudinal extraction
• optimize transfer from gas cell to Penning traps
• improve detection efficiency (Dali detector, channeltron)
• non destructive detection (FT-ICR)
Outlook (II) - FT-ICR detection
z
P enning Trap
S EGM EN T ED ELECT RO DE
excited ion at cyclotron orbit
I
FFTSpectrumA na lyze r
low noiseam plifier
tim e freque ncy
d P /d f
induced ac-curren t m ass spectrum
F F T
I
B-fie ld
FT-ICR detection :signal-to-noise ratio for a single ion
CkT
D
r
2N
S ion
L . .
z
C . .
II o n
II o n
LC
1
m
BqLC
Requirements for a high
sensitivity (q = 1, A ≈ 250):
• large ion radius
• small trap size
• high quality factor Q
• low temperature
• low capacitance
FT-ICR AT SHIPTRAP
7 T - Magnet
Measurement TrapPurification Trap
4K Electronics
77K Filter Bank
FFT Analyser Broad BandFFT Analyser
narrow-band FT-ICR detection:
• highly sensitive mass spectrometry
on rare nuclei
broad-band FT-ICR detection:
• identification of the trap‘s contents
• study of chemical reaction kinetics
77 K
S. Stahl, PhD thesis C. Weber
THE CRYOGENIC PURIFICATION TRAP
Thank you for your attention!
SHIPTRAP collaboratorsGSI / SHIPTRAPM. Block
D. Beck
F. Herfurth
H.-J. Kluge
C. Kozhuharov
M. Mukherjee
W. Quint
S. Rahaman
C. Rauth
M. Suhonen
C. Weber
GSI / SHIP
D. Ackermann
F. P. Hessberger
S. Hofmann
G. Münzenberg
Greifswald
M. Breitenfeld
G. Marx
L. Schweikhard
Mainz
H. Backe
A. Dretzke
R. Horn
T. Kolb
W. Lauth
Giessen
S. Eliseev
H. Geissel
C. Scheidenberger
M. Petrick
W. Plaß
Z. Wang
Munich
D. Habs
S. Heinz
J. Neumayr
P. Thirolf
Former PhD studentsJ. DillingG. SiklerD. Rodríguez
magnetron motion
cyclotron motion
axial motion
Magnetron motion: E x B drift
Axial motion: oscillation in E-field
Reduced cyclotron motion:
242
22zcc
242
22zcc
20
md
qVz
Bm
qc
Penning trap basics
r0
z 0
Ф0
B
for mass measurements: