Laser spectroscopy of radioactive atoms embedded in superfluid He, and a planned nuclear structure study on proton-rich Ag isotopes -“OROCHI” project - Takeshi Furukawa Tokyo Institute of Technology International Workshop on Physics of Nuclei at Extremes, ‘10 1/26 Tokyo TECH
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Laser spectroscopy of radioactive atoms embedded in superfluid He ,
International Workshop on Physics of Nuclei at Extremes, ‘10 1/26 Tokyo TECH. Laser spectroscopy of radioactive atoms embedded in superfluid He , and a planned nuclear structure study on proton-rich Ag isotopes - “OROCHI” project -. Tokyo Institute of Technology. Takeshi Furukawa. - PowerPoint PPT Presentation
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Laser spectroscopy of radioactive atomsembedded in superfluid He,
and a planned nuclear structure studyon proton-rich Ag isotopes
-“OROCHI” project -
Laser spectroscopy of radioactive atomsembedded in superfluid He,
and a planned nuclear structure studyon proton-rich Ag isotopes
-“OROCHI” project -
Takeshi FurukawaTokyo Institute of Technology
International Workshop on Physics of Nuclei at Extremes, ‘10 1/26 Tokyo TECH
ContentsContentsContentsContents・ What is “OROCHI” ? nuclear laser spectroscopy in superfluid helium for the measurement of rare isotopes not with high precision , but with sensitive to detect photons
・ What is “OROCHI” ? nuclear laser spectroscopy in superfluid helium for the measurement of rare isotopes not with high precision , but with sensitive to detect photons
・ Present status of “OROCHI” off-line development with Rb, Cs, Ag, and Au stable isotopes
・ Present status of “OROCHI” off-line development with Rb, Cs, Ag, and Au stable isotopes
・ Future prospect of “OROCHI” on-line experiment plan for proton-rich Ag isotopes
・ Future prospect of “OROCHI” on-line experiment plan for proton-rich Ag isotopes
IWPNE 2010, 2010 1/26 Tokyo TECH, T. Furukawa
nuclear spins
Nuclear structure
IWPNE 2010, 2010 1/26 Tokyo TECH, T. Furukawa
one of the most important quantities for nuclear structure investigation ex) orbital angular momentum of valence nucleons, configuration mixing …..
Introduction: Measurement of Nuclear Spin and MomentIntroduction: Measurement of Nuclear Spin and Moment
electromagnetic moments
interaction between atomic spin mF and
external magnetic field
hyperfine interactions
Laser spectroscopy
atomic sublevel structure
IJ
e
IJ
F
external magnetic
field B
hyperfine structuresZeeman splittings
interaction between nuclear moments
and electronsNuclear spin/moment measurement on unstable nuclei far from stability line : difficult - low yield - large contamination - small polarization
However...
New Laser SpectroscopyNew Laser Spectroscopy
“laser spectroscopy for radioisotope atoms in superfluid helium (He II)”
to measure the nuclear spins & moments in exotic nuclei…
“OROCHI ”“OROCHI ”Optical Radioisotope-atom Observation in Condensed Helium as Ion-catcher
Laser
Ion beam
(radioisotope beam) Separator
(i.e. BigRIPS in RIKEN)Accelerator (i.e. SRC in RIKEN)
RI beam
target
LIF
He II
((((((
radiowaveor
microwave
hyperfine structure Zeeman structure
nuclear momentnuclear spin
IWPNE 2010, 2010 1/26 Tokyo TECH, T. Furukawa
from “DRAEMON” vol. 22, by FUJIKO, F. Fujio
光波長 (nm)
Inte
nsit
y (
arb
.un
it)
133Cs atomic spectra in He II
① blue-shifted(
absorption
in vacuum
emission
Excited with expanding the surrounding He
He II
atom
Laser
Detector
wavelength: LIF≠laserSuppress background
countReduction:10-10 ~ 10-13
He II
Advantage in HeAdvantage in He IIIIAdvantage in HeAdvantage in He IIII
② broadened
Wavelength (nm)
We use He II
Atomic absorption spectra in He II
to reduce the b.g. photons.
IWPNE 2010, 2010 1/26 Tokyo TECH, T. Furukawa
IWPNE 2010, 2010 1/26 Tokyo TECH, T. Furukawa
Laser
RI beam
absorb & emit photons cyclically
→ detect much photons/atom(typically ~ 105-108 photons /sec)
→ good statistic !!
Contaminant atoms: do not absorb laser light
→ observe only objective atoms !!
Laser induced fluorescence (LIF) photon
Advantages of laser spectroscopyAdvantages of laser spectroscopy
Scattered laser photon
B
laser
atoms
m = -1/2 m = +1/2
S1/2
P1/2σ+
XD1 Lineσ+
m = +3/2
measurement of atomic sublevel structure : Double resonance spectroscopy
・ determine nuclear spin & moment : Cs, Rb isotopes
IWPNE 2010, 2010 1/26 Tokyo TECH, T. Furukawa
・ Producing high polarization in alkali Cs, Rb atoms
next step: On-line experiment
・ applying to Ag and Au atoms : successfulCan we apply this OROCHI to atoms other than alkali?
Z
N
N =82
Z =50
N =50
Stable line
g.s. moment is unknown
g.s. moment is known
g.s. moment is zero (even-even nuclei)
Stable isotope
N. J. Stone, At. Nucl. Data Tab. 90, 75 (2005)
Future prospectFuture prospect
measurable
1st goal :exotic N=Z nucleus 94Ag I, of g.s. and isomer state (21+) expected yield: < 1 pps (with BigRIPS)
RI (total): 0.1 ppsIsomer ratio: 5 % (from RIBF facility)1 day measurement
simulationsimulation
IWPNE 2010, 2010 1/26 Tokyo TECH, T. Furukawa
IWPNE 2010, 2010 1/26 Tokyo TECH, T. Furukawa
On-line experiment with Rb beam- 1st trial -
On-line experiment with Rb beam- 1st trial -
Rb beam
laser
cryostat
All the devices were mounted on RIKEN RIPS beam line !!All the devices were mounted on RIKEN RIPS beam line !!
Oh, my god......
But Rb beam has not accelerated due to machine trouble…But Rb beam has not accelerated due to machine trouble…
Rb beam
Cryostat
Photo-detection system
The result will be shown next time …The result will be shown next time …
ConclusionConclusion
“OROCHI ” Project“OROCHI ” ProjectOptical Radioisotope-atom Observation in Condensed Helium as Ion-catcher
-We developed the new laser spectroscopy method “OROCHI” for determining nuclear spins and moments of exotic RI far from stability by using superfluid helium (He II) as a stopper of RI beam and host matrix of laser spectroscopy.
- Atomic spectra in He II (largely blue-shifted and broadened) enable us to measure for the extremely low yield RI whose yield is less than 1 pps.
- In our off-line development using stable Rb and Cs isotopes, we have successfully demonstrated the determination of nuclear spins and moments from the measured Zeeman and hyperfine splitting respectively. We have also demonstrated the optical pumping and double resonance of stable Ag and Au isotopes in recently.
We hope This OROCHI will open the door to measure the nuclear spins and momentsof exotic nuclei, particularly proton drip-line, N=Z nucleus 94Ag
- Preparation of setups for online experiment is almost finished.
IWPNE 2010, 2010 1/26 Tokyo TECH, T. Furukawa
RIKEN : H. Ueno, N. Aoi, A. Yoshimi, K. Yoneda, Y. Togano, M. Takechi, Y. Ichikawa, S. Nishimura, M, Nishimura, T. Kobayashi, M. Wada, T. Sonoda, A. Takamine, T. Motobayashi, …
Osaka Univ.: M. Kazato, T. Shimoda, A. Odahara
CYRIC, Tohoku Univ.: A. Sasaki, T. Wakui, H. Oouchi, S. Izumi, T. Shinozuka
Meiji Univ.: Y. Matsuura, H. Kato
OROCHI - CollaboratorOROCHI - Collaborator
Tokyo Univ. of Agriculture and Tech. : A. Hatakeyama
Tokyo institute of Technology: K. Asahi, Y. Kondo
Spokesperson: Takeshi Furukawa (Tokyo Institute of Techinology), Yukari Matsuo (RIKEN)