Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 48 (2015)

Hyperfine structure measurement of 133 Cs atoms in superfluid helium
K. Imamura,∗1,∗2 T. Furukawa,∗3 X. F. Yang,∗4 Y. Mitsuya,∗2 T. Fujita,∗5 M. Hayasaka,∗6∗2∗9T. Kobayashi,∗7 A. Hatakeyama,∗8 H. Ueno,∗1 H. Odashima,
133 and Y. Matsuo

Hyperfine structure measurement ofCs atoms in superfluid helium

∗5∗6
∗7
∗8
∗9

LIF Intensity [count/bin]

LIF Intensity [count/bin]

LIF Intensity [count/bin]

LIF Intensity [count/bin]

nm)5) . In this experiment, several gauss of static magThe study of nuclear structure via laser spectroscopy
∗1,∗2
∗3
∗4
∗2
∗6K.
Imamura,T.
Furukawa,
X.
F. Yang,
Mitsuya,T.trappedFujita,∗5atoms
M. Hayasaka,
neticﬁeld wasY.applied
to theusing atechniques has contributed to signiﬁcant progress in∗7
∗8
∗1
∗2
∗9
T. Kobayashi,
A. Hatakeyama,
Ueno, H.
Odashima,
Y. polarization.
Matsuopair ofH.
Helmholtz
coils
to maintainandspinnuclear physics1) . To extend
the applicabilityofTo observe HFS resonance of Cs atoms, MW was irralaser spectroscopy techniques for the study of lowdiated to the spinpolarized
atoms andseveral
its frequency
yield exotic nuclei
rate is lessnm)5). In this Cs
experiment,
gauss of static magThewhose
study productionof nuclear structure
via thanlaser spectroscopy
was scanned.
The ﬁeld
emittedinducedﬂuorescence
100 pps, we havebeen developing
OROCHI(Optical progress
neticwaslaser
appliedto thetrapped atoms using atechniques
has contributed
to signiﬁcantin1)(LIF) during
the scanningof MW
frequencies
wasspinde- polarization.
RI-atom Observationin Condensed
pairof Helmholtz
coils
to maintain
nuclear physics. To Helium
extend as
theIonapplicabilityof2)
using aTophotomultipliertube. To suppress
strayMW was irracatcher) . OROCHI
is based on
a combination
observe HFS resonanceof Cs atoms,
laser spectroscopy
techniques
for theofstudytectedof lowlightthan
from thediatedlaser beam,
the wavelength
LIF (892superﬂuid heliumII)nuclei
as anwhoseeﬀective
stopper rate
for is lessto the spinpolarized Csofatoms
and its frequency
yield (Heexotic
production5)
high-energetic100
ion pps,beams
in beensitu laser
spectroscopy
was selectedusing a monochromator.
1 ﬂuorescence
was scanned.
The emitted laserFigure
inducedweand
have
developing
OROCHI nm)(Opticalof atoms. InRI-atom
OROCHI,an energetic
beam prothe obtained
spectratheinscanning
this experiment.
We(LIF) duringof MW frequencies
was deObservationin ionCondensed
Heliumshows
as Ionduced at an accelerator
is directly
injected
can clearlyresonance
peaks in theﬁgure.
tected theusinga photomultipliertube.
To suppress straycatcher)2) .facility
OROCHIis basedon ainto
combinationof observe
He II. The injectedionshelium
are neutralized
the stopper
Since forthe resonancefrequencies
are shiftedby ZMS of LIF (892light fromthe laser beam,
the wavelength
superﬂuid(He II) as during
an eﬀective
stopping process
and are trapped
as andisolated
atoms.
owing to the appliedmagneticﬁeld,thearesonancefrenm)5) was
high-energetic
ion beams
in situlaser spectroscopy
selectedusing
monochromator.
Figure 1
The trapped ofatomsare subjected
to aancircularly
quencies
measuredboth cases
i.e.,in using
σ+atoms.
In OROCHI,
energeticpoion beampro- are shows
the forobtained
spectrathis experiment.
We−larized laser duced
light andto thespin ispolarized
and σinto
polarized
lasers. observe
The HFSCs atoms peaks
in He in the ﬁgure.
at andriven
accelerator
facility
directly injected
can clearly
theofresonancestate. The Zeeman/hyperﬁnesplittings(ZMS/HFS)
II is calculated
by averaging
the twomeasured
He II. The injectedions areneutralized during
theSince
the resonancefrequencies
areresoshifted by ZMS
of atoms are stopping
measuredprocessusing aandlaser-RF/MW
frequencies.
obtainthe preliminary
value
are trapped(radioas isolatednanceatoms.
owingWeto theappliedmagnetic ﬁeld,
theofresonance frefrequency/microwave)
doubleresonance
method to
9 250.58(2)MHz
as theof Cs foratoms
in cases
He II.i.e., using σ +The trappedatoms
are subjected
to dea circularly
poquencies
areHFS
measuredboth−
duce nuclear spins
andmoments.
Sofar,
aseriesofexThis
resultshowsthat
theHFSofCs
atomsin
II atoms in He
larized laser light and driven to the spin polarizedand σ polarized lasers. The HFS Heof Cs
periments using
the 84-87
is approximately
0.63(2)%largerthanthatinvacion beam have beenper- (ZMS/HFS)
state.
The RbZeeman/hyperﬁnesplittings
II is calculated by averaging the two measured resouum
owing tonancethe frequencies.
eﬀect of the We
surrounding
formed at theofRIKEN
Nishina
Center.
The
feasibilatoms aremeasuredusing
a laser-RF/MW(radioobtain thehelium.
preliminary value ofThetoachieved
accuracy
6 digitsin the
ity of the principleof OROCHI hasdouble
been successfully
frequency/microwave)
resonance method
de9measurement250.58(2) MHz
as theis HFSof Cs
atoms in He II.
3)current
theshows
accuracy
HFS
demonstratedduceby measuring
the ZMSof 84-87 RbSo. far,
For a series
nuclear spins
and moments.
of ex-system.
ThisSince
resultthat ofthethe
HFSof ofCsCs
atoms in He II
atoms
in He IIisisapproximately
limited owing to
the ﬂuctuation
the that in vacfurther developmentof using
OROCHI,
it isRbindispensable
periments
the 84-87
0.63(2)% largerinthan
ion beam have been
perappliedﬁeld, ofit thecan surrounding
be imto ensure theformed
applicability
OROCHIfor themea- Theintensityuumowingmagnetic
to the eﬀect
helium.
at the ofRIKEN
Nishina
Center.
feasibil- of theproved by oneTheor twoordersmeasurementof magnitude accuracy
by installing
surement of HFS
atoms
in He ofII. OROCHI
In particular,
the successfully
achieved
is 6 digits in the
ity ofoftheprinciple
has been
3)
stabilized
supplyfor theSince
magneticﬁeld. Inofthefollowing two demonstrated
issues have to beHowthe ofHe84-87 Rbcurrentsystem.
the accuracy
the HFS of Cs
byconﬁrmedmeasuringi)theZMS. For power
near feature, wewillinconduct
measurement
II environmentaﬀectsdevelopment
the HFS of anatoms
He II issystematic
limited owing
to the ﬂuctuation in thefurtherof introduced
OROCHI, atom,
it is indispensable
84-87of HFSand ii) What tois ensure
the highest
level of measurementac- for theRb toofdemonstratefeasibility
the applied themagnetic
ﬁeld,ofit can be imthe applicabilityof OROCHI
mea-using intensity
curacy that canbe achieved.
theII.above
OROCHI
the studyof low-yield
exoticofnuclei.
by oneor two orders
magnitude by installing
surementof HFSToofinvestigate
atoms in He
In particular,
the for proved
mentioned issues,
we conducted
an experimentusingi) How the Hestabilized power supply3 for the magnetic ﬁeld. In thefollowing
two issues haveto be conﬁrmed
10
103
133
Cs atoms thatare introduced
intoII using
thenear feature, we will
II environmentaﬀectstheHeHFSof an introduced
atom,
5.5 conduct systematic measurement+84-87
σ pumpinglaser ablationand
technique.
of HFS usingii) What is the highest level of measurement
acRb todemonstrate the feasibility ofσ- pumping11 (F, m )=(4, +4) (3, +4))=(4, +4) (3,+4)
The experimental
setup
to theone incuracy thatcanisbesimilarachieved.
To investigate
the above F OROCHI for the study(F,ofmFlow-yield
exoticnuclei.
ref.[4]. An open-topped
quartz we
cubic
cell (70 ××
mentioned issues,
conducted
an70
experiment
using
4.5
103
103
70 mm3 ) ﬁlled133withHe II liquidwasintroduced
placed inside
Cs atoms
that areintothe
He II using9 the5.5
σ+ pumping
cryostat. A solid
was placed
approximately 1 cm
laserCsCl
ablationtechnique.
σ- pumping11 (F, mF)=(4, +4) (3, +4)(F, mF)=(4, +4) (3, +4)
above the liquidThesurface.
In this experiment,atomsto the one
experimental
setup is Cs
similarin7
3.5
were introduced
into AnHe open-topped
II using two quartz
pulsed cubic
lasers4). (70 × 70 ×ref.[4].
cell4.5
39242.3 9242.5 9242.7 9242.9
9
The introduced
into the70 Cs
mmatoms) ﬁlledwere
withpumped
He II liquid
wasspinplaced inside 9258.5
the9258.9
9258.7
Frequency [MHz]
polarized stateusing circularly
polarized
laser approximately
tuned
cryostat.
A solid CsCl
was placed
1 cm Frequency [MHz]
Fig.atoms
1. Observed spectra in this experiment. (a) when usto the D1 transitionof Cs
atomsIninthis
Heexperiment,
II (876
above thelineliquidsurface.
Cs7
3.5
ing 4)
thewere introduced into He II using two pulsed lasers. σ + pumping laser. (b) when using the σ − pump∗1 RIKEN Nishina Center
9242.3 9242.5 9242.7 9242.9
laser.
introduced Cs atoms were pumped into theing
spin9258.5
9258.9
9258.7
∗2 DepartmentTheof Physics, Meiji University
Frequency [MHz]
Frequency[MHz]
state
using
circularly
polarized
laser
tuned
∗3 Departmentpolarized
Referencesof Physics, Tokyo Metropolitan University∗4 School of Physics,
Fig.
in thisexperiment.
to thePeking
D1 transition
Cheal andK.1.T.Observed
Flanagan:spectra
J. Phys.
G Nucl.
Partic. (a) when usUniversity line of Cs atoms in He1)IIB.(876
Department of Physics, Osaka University
ing the σ + pumping laser. (b) when using the σ − pump37, 113101 (2010).
Department∗1of Physics,Tokyo Gakugei
RIKEN Nishina
Center University
2) T. Furukawa eting
al.:laser.
Hyp. Interact. 196, 191 (2010).
∗2 for
RIKEN Center
AdvancedofPhotonics
Department
Physics, Meiji University
3) X. F. Yang References
et al.: Phys. Rev. A 90, 052516 (2014).
∗3
Department of AppliedPhysics,Tokyo Tokyo
Universityof Agri- University
Departmentof Physics,Metropolitan
4) T. Furukawa
Phys.
Rev.
96, 095301(2006).G Nucl. Partic.
culture and ∗4technology
1)etB.al.:ChealandK. Lett.
T. Flanagan:
J. Phys.
School of Physics, Peking University∗55)
T.
Kinoshitaetal.:
Phys.
Rev.
B
49,3648(1994).
Department of Advanced
Sciences,
HoseiOsaka
University
Departmentof Physics,
University
37, 113101 (2010).
∗6 Department of Physics, Tokyo Gakugei University2)
T.
Furukawa et al.: Hyp. Interact. 196, 191 (2010).
∗7 RIKEN Center for Advanced Photonics
3) X. F. Yang et al.: Phys. Rev. A 90, 052516 (2014).
∗8 Department of Applied Physics, Tokyo University of Agri4) T. Furukawa et al.: Phys. Rev. Lett. 96, 095301 (2006).
culture and technology- 251 ∗9 Department of Advanced Sciences, Hosei University5) T. Kinoshita et al.: Phys. Rev. B 49, 3648 (1994).

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