Review articles

### Nuclear clocks based on resonant excitation of gamma-transitions

E. Peik and M. Okhapkin

arXiv:1502.07322 and Comptes Rendus Physique 16, 5 (2015)

### Prospects for a Nuclear Optical Frequency Standard based on Thorium-229

E. Peik, K. Zimmermann, M. Okhapin, and Chr. Tamm

arXiv:0812.3548 (2008)

### Properties of the optical transition in the 229Th nucleus

E. V. Tkalya

Physics Uspekhi 46, 315-324 (2003)

### Lasers as a bridge between atomic and nuclear physics

S. Matinyan

Phys. Rep. 298, 199-249 (1998)

Theory: Properties of the isomer

### Hyperfine Structure in Th229g3+ as a Probe of the Th229g→Th229m Nuclear Excitation Energy

K. Beloy

Phys. Rev. Lett. 112, 062503 (2014)

### Magnetic dipole and electric quadrupole moments of the 229Th nucleus

M. S. Safronova, U. I. Safronova, A. G. Radnaev, C. J. Campbell, and A. Kuzmich

Phys. Rev. A 88, 060501(R) (2013)

### On the Energy of the 3.5-eV Level in 229Th

S. L. Sakharov

Physics of Atomic Nuclei 73, 1 (2010)

### Nuclear structure of lowest Th229 states and time-dependent fundamental constants

E. Litvinova, H. Feldmeier, J. Dobaczewski, and V. Flambaum

Phys. Rev. C 79, 064303 (2009)

### Energy of the 3/2+ state of Th229 reexamined

Z.O. Guimarães-Filho, and O. Helene

Phys. Rev. C 71, 044303 (2005)

### Matrix element of the anomalously low-energy (3.5 +/-0.5) eV transition in 229Th and the isomer lifetime

A. M. Dykhne and E. V. Tkalya

JETP 67, 251 (1998)

### Processes of the nuclear isomer 229mTh(3/2+, 3.5 ± 1.0 eV) resonant excitation by optical photons

E. V. Tkalya, V. O. Varlamov, V. V. Lomonosov, and S. A. Nikulin

Phys. Scr. 53, 296-299 (1996)

Theory: Drifts in fundamental constants

### Constraining the Evolution of the Fundamental Constants with a Solid-State Optical Frequency Based on the 229Th Nucleus

G. Rellergert, D. DeMille, R. R. Greco, M. P. Hehlen, J. R. Torgerson, and E. R. Hudson

Phys. Rev. Lett. 104, 200802 (2010)

### Proposed Experimental Method to determine α Sensitivity of Splitting between Ground and 7.6 eV Isomeric States in 229-Th

J. C. Berengut, V. A. Dzuba, V. V. Flambaum, and S. G. Porsev

Europhys. Lett. 85, 50 005 (2009)

### Splitting sensitivity of the ground and 7.6 eV isomeric states of 229Th

A. C. Hayes, J. L. Friar, and P. Möller

Phys. Rev. C 78, 024311 (2008)

### Temporal variation of the fine structure constant and the strong interaction parameter in the 229-Th transition

X.-T. He and Z.-Z. Ren

Nucl. Phys. A 806, 117 (2008)

### Sensitivity of nuclear transition frequencies to temporal variation of the fine structure constant or the strong interaction

A. C. Hayes and J. L. Friar

Phys. Lett. B 650, 229 (2007)

### Enhanced Effect of Temporal Variation of the Fine Structure Constant and the Strong Interaction in 229-Th

V. V. Flambaum

Phys. Rev. Lett. 97, 092502 (2006)

### The fundamental constants and their variation: observational and theoretical status

J. P. Uzan

Rev. Mod. Phys. 75, 403 (2003)

There is also a similar long review by J. P. Uzan that appeared in 2011 and briefly mentions 229Th, in particular discrepancies in the works listed above.

Theory: Proposals for applications

### Radiative emission of neutrino pair from nucleus and inner core electrons in heavy atoms

M. Yoshimura and N. Sasao

Phys. Rev. D 89, 053013 (2014)

This paper is accompanied by two more recent publications, Phys. Rev. D 90, 013022 (2015) and Phys. Rev. D 91, 063516 (2014), which provide further details.

### Quantum interference effects in an ensemble of 229Th nuclei interacting with coherent light

S. Das, A. Palffy, and C.H. Keitel

Phys. Rev. C 88, 024601 (2013)

### Coherence-Enhanced Optical Determination of the 229Th Isomeric Transition

W.-T. Liao, S. Das, C. H. Keitel, and A. Pálffy

Phys. Rev. Lett. 109, 262502 (2012)

### Proposal for a Nuclear Gamma-Ray Laser of Optical Range

E.V. Tkalya

Phys. Rev. Lett. 106, 162501 (2011)

### Nuclear Quantum Optics with X-Ray Laser Pulses

T. J. Bürvenich, J. Evers, and C. H. Keitel

Phys. Rev. Lett. 96, 142501 (2006)

### 229mTh (3/2+, 3.5 eV) and a check of the exponentiality of the decay law

A. M. Dykhne and E. V. Tkalya

JETP 67, 549 (1998)

Optical nuclear clock

### Single-Ion Nuclear Clock for Metrology at the 19th Decimal Place

C. J. Campbell, A. G. Radnaev, A. Kuzmich, V. A. Dzuba, V. V. Flambaum, and A. Derevianko

Phys. Rev. Lett. 108, 120802 (2012)

### Nuclear laser spectroscopy of the 3.5 eV transition in Th-229

E. Peik and Chr. Tamm

Europhys. Lett. 61, 181 (2003)

Optical atomic clocks

### Systematic evaluation of an atomic clock at 2 x 10^{-18} total uncertainty

T.L. Nicholson, S.L. Campbell, R.B. Hutson, G.E. Marti, B.J. Bloom, R.L. McNally, W. Zhang, M.D. Barrett, M.S. Safronova, G.F. Strouse, W.L. Tew, and J. Ye

Nat. Commun. 6, 6896 (2015)

### Optical atomic clocks

N. Poli, C. W. Oates, P. Gill and G. M. Tino

arXiv:1401.2378 (2014)

The original paper is kind of hard to find: Riv. Nuovo Cim. 36, 555-624 (2013).

### Optical atomic clocks

A. D. Ludlow, M. M. Boyd, J. Ye, E. Peik, and P. O. Schmidt

Rev. Mod. Phys. 87, 637 (2015)

Gamma spectroscopy measurements

### Prospects for measuring the 229Th isomer energy using a metallic magnetic microcalorimeter

G. A. Kazakov, V. Schauer, J. Schwestka, S. Stellmer, J. H. Sterba, A. Fleischmann, L. Gastaldo, A. Pabinger, C. Enss, and T. Schumm

Nucl. Instr. Meth. Phys. Res. A, 735, 229 (2014) and arXiv:1306.3069.

### Improved Value for the Energy Splitting of the Ground-State Doublet in the Nucleus 229mTh

B. R. Beck, C.Y. Wu, P. Beiersdorfer, G. V. Brown, J. A. Becker, K. J. Moody, J. B. Wilhelmy, F. S. Porter, C. A. Kilbourne, and R. L. Kelley

LLNLPROC-415170 (2009)

### Energy Splitting of the Ground-State Doublet in the Nucleus 229-Th

B. R. Beck, J. A. Becker, P. Beiersdorfer, G.V. Brown, K. J. Moody, J. B. Wilhelmy, C. A. Kilbourne, and R. L. Kelley

Phys. Rev. Lett. 98, 142501 (2007)

### Nuclear structure of 229-Th

E. Ruchowska et al.

Phys. Rev. C 73, 044326 (2006)

### Nuclear structure of 229Th from γ-ray spectroscopy study of 233U α-particle decay

V. Barci, G. Ardisson, G. Barci-Funel, B. Weiss, O. El Samad, and R. K. Sheline

Phys. Rev. C 68, 034329 (2003)

### The nuclear structure of 229Th

K. Gulda et al., ISOLDE collaboration

Nucl. Phys. A 703, 45 (2002)

### An excited state of 229Th at 3.5 eV

R. G. Helmer and C. W. Reich

Phys. Rev. C 49, 1845 (1994)

### Energy separation of the doublet of intrinsic states at the ground state of 229Th

C. W. Reich and R. G. Helmer

Phys. Rev. Lett. 64, 271 (1990)

### The decay of 233U

M. J. Canty, R. D. Connor, D. A. Dohan, and B. Pople

J. Phys. G: Nucl. Phys. 3 (3), 421 (1977)

### Features of the low-energy level scheme of 229Th as observed in the a-decay of 233U

L. A. Kroger and C.W. Reich

Nuclear Physics A 259, 29 (1976)

Alpha decay of the isomer: experiments between 1994 and 2007

### Half-life estimation of the first excited state of 229Th by using a-particle spectrometry

H. Kikunaga, Y. Kasamatsu, H. Haba, T. Mitsugashira, M. Hara, K. Takamiya, T. Ohtsuki, A. Yokoyama, T. Nakanishi, and A. Shinohara

Phys. Rev. C 80, 034315 (2009)

### Search for a “3.5-eV isomer” in 229-Th in a hollow-cathode electric discharge

T. T. Inamura and H. Haba

Hyperfine Interactions 171, 197 (2006)

### Search for α-decay of 229mTh produced from 229Ac β-decay following 232Th(γ, p2n) reaction

H. Kikunaga, Y. Kasamatsu, K. Takamiya, T. Mitsugashira, M. Hara, T. Ohtsuki, H. Yuki, A. Shinohara, S. Shibata, N. Kinoshita, A. Yokoyama, T. Nakanishi

Radiochimica Acta 93, 507 (2005) and here

### Pumping 229mTh by Hollow-Cathode Discharge

T. T. Inamura, T. Mitsugashira, and the Oarai Collaboration

Hyperfine Interactions 162, 115 (2005)

### Alpha-decay from the 3.5 eV isomer of 229Th

T. Mitsugashira, M. Hara, T. Ohtsuki, H. Yuki, K. Takamiya, Y. Kasamatsu, A. Shinohara, H. Kikunaga, and T. Nakanishi

Journal of Radioanalytical and Nuclear Chemistry 255, 63 (2003)

Optical decay of the isomer: experiments between 1994 and 2007

### Search for the decay of 229mTh by photon detection

Y. Kasamatsu, H. Kikunaga, K. Takamiya, T. Mitsugashira, T. Nakanishi, Y. Ohkubo, T. Ohtsuki, W. Sato, and A. Shinohara

Radiochim. Acta 93, 511 (2005) and here

### Search for a low-lying 3.5-eV isomeric state in 229Th

I.D. Moore, I. Ahmad, K. Bailey, D. L. Bowers, Z.-T. Lu, T. P. O’Connor, and Z. Yin

Argonne Physics Division Report PHY-10990-ME-2004 (2004)

### Search for decay of the 3.5-eV level in 229-Th

E. Browne, E. B. Norman, R. D. Canaan, D. C. Glasgow, J. M. Keller, and J. P. Young

Phys. Rev. C 64, 014311 (2001)

### Reexamination of the Optical Gamma Ray Decay in 229-Th

S. B. Utter, P. Beiersdorfer, A. Barned, R. W. Lougheed, J. R. Crespo Lopez-Urrutia, J. A. Becker, and M. S. Weiss

Phys. Rev. Lett. 82, 505 (1999)

### Spontaneous Ultraviolet Emission from 233Uranium/229Thorium Samples

R. W. Shaw, J. P. Young, S. P. Cooper, and O. F. Webb

Phys. Rev. Lett. 82, 1109 (1999)

### Ultraviolet Photon Emission Observed in the Search for the Decay of the 229Th Isomer

D. S. Richardson, D. M. Benton, D. E. Evans, J. A. R. Griffith, and G. Tungate

Phys. Rev. Lett. 80, 3206 (1998)

### Observation of Electromagnetic Radiation from Deexcitation of the 229-Th Isomer

G. M. Irwin and K. H. Kim

Phys. Rev. Lett. 79, 990 (1997)

Further experiments

### The search for the existence of ^{229m}Th at IGISOL

V. Sonnenschein, I. D. Moore, S. Raeder, A. Hakimi, A. Popov, and K. Wendt

Eur. Phys. J. A 48: 52 (2012)

### Determination of the ground-state hyperfine structure in neutral 229Th

V. Sonnenschein, S. Raeder, A. Hakimi, I.D. Moore, and K. Wendt

J. Phys. B: At. Mol. Opt. Phys. 44, 165005 (2012)

### Resonance ionization spectroscopy of thorium isotopes – towards a laser spectroscopic identification of the low-lying 7.6 eV isomer of 229Th

S. Raeder, V. Sonnenschein, T. Gottwald, I.D. Moore, M. Reponen, S. Rothe, N. Trautmann, and K. Wendt

J. Phys. B: At. Mol. Opt. Phys. 44, 165005 (2011)

### Determination of the half-life of the ground state of 229Th by using 232U and 233U decay series

H. Kikunaga, T. Suzuki, M. Nomura, T. Mitsugashira, and A. Shinohara

Phys. Rev. C 84, 014316 (2011)

### Nuclear structure of ^{229,231}Th studied with the ^{230,232}Th (d, t) reactions

D. G. Burke, P. E. Garrett, T. Qu, and R. A. Naumann

Nucl. Phys. A 809, 129 (2008)

### Additional evidence for the proposed excited state at 5 eV in 229Th

D. G. Burke, P. E. Garrett, T. Qu, and R. A. Naumann

Phys. Rev. C 42, R499 (1990)

### Nuclear radii of thorium isotopes from laser spectroscopy of stored ions

W. Kälber, J. Rink, K. Bekk, W. Faubel, S. Göring, G. Meisel, H. Rebel, and R. C. Thompson

Z. Phys. A 334, 103-108 (1989)

### Coulomb excitation of states in 229Th

C. E. Bemis, F. K. McGowan, J. L. C. Ford, Jr., W. T. Milner, R. L. Robinson, P. H. Stelson, G. A. Leander, and C. W. Reich

Phys. Scr. 38, 657-663 (1988)

The crystal approach

### Radioluminescence and photoluminescence of Th:CaF2 crystals

Simon Stellmer, Matthias Schreitl, and Thorsten Schumm

arXiv:1506.01938 (2015)

### 229Thorium-doped calcium fluoride for nuclear laser spectroscopy

P. Dessovic, P. Mohn, R. A. Jackson, G. Winkler, M. Schreitl, G. Kazakov, and T. Schumm

J. Phys.: Condens. Matter 26, 105402 (2014)

### Optical spectroscopy of an atomic nucleus: Progress toward direct observation of the 229Th isomer transition

M. P. Hehlen, R. R. Greco, W. G. Rellergert, S. T. Sullivan, D. DeMille, R. A. Jackson, E. R. Hudson, and J. R. Torgerson

Journal of Luminescence 133, 91 (2013)

### Performance of a 229-Thorium solid-state nuclear clock

G. A. Kazakov, A. N. Litvinov, V. I. Romanenko, L. P. Yatsenko, A. V. Romanenko, M. Schreitl, G. Winkler, and T. Schumm

arXiv:1204.3268 and New J. Phys. 14, 083019 (2012)

### Progress towards fabrication of Th:229-doped high energy band-gap crystals for use as a solid-state optical frequency reference

W. G. Rellergert, S. T. Sullivan, D. DeMille, R. R. Greco, M. P. Hehlen, R. A. Jackson, J. R. Torgerson, and E. R. Hudson

arXiv:1011.0769 (2011)

### Optical transition of the 229Th nucleus in a Solid-state environment

W. G. Rellergert, D. DeMille, R. R. Greco, M. P. Hehlen, J. R. Torgerson, and E. R. Hudson

arXiv:0905.2230 (2009)

### Computer modelling of thorium doping in LiCaAlF6 and LiSrAlF6: application to the development of solid state optical frequency devices

R. A. Jackson, J. B. Amaral, M. E. G. Valerio, D. P. DeMille and E. R. Hudson

J. Phys.: Condens. Matter 21, 325403 (2009)

The ion trap approach

### Observation of an unexpected negative isotope shift in 229Th+ and its theoretical explanation

M.V. Okhapkin, D.M. Meier, E. Peik, M.S. Safronova, M.G. Kozlov, and S.G. Porsev

Phys. Rev. A 92, 020503 (2015)

### Energy levels of Th+ between 7.3 and 8.3 eV

O. A. Herrera-Sancho, N. Nemitz, M. V. Okhapkin, and E. Peik

Phys. Rev. A 88, 012512 (2013)

### Generation of thorium ions by laser ablation and inductively coupled plasma techniques for optical nuclear spectroscopy

V.I. Troyan, P.V. Borisyuk, R.R. Khalitov, A.V. Krasavin, Yu.Yu. Lebedinskii, V.G. Palchikov, S.S. Poteshin, A.A. Sysoev, and V.P. Yakovlev

Las. Phys. Lett. 10, 105301 (2013)

### Laser ablation loading of a radiofrequency ion trap

K. Zimmermann, M. V. Okhapkin, O. A. Herrera Sancho, and E. Peik

Appl. Phys. B 107, 883 (2012)

### Observation of the 717-nm electric quadrupole transition in triply charged thorium

A. G. Radnaev, C. J. Campbell, and A. Kuzmich

Phys. Rev. A 86, 060501(R) (2012)

### Two-photon laser excitation of trapped 232Th+ ions via the 402-nm resonance line

O. A. Herrera-Sancho, M. V. Okhapkin, K. Zimmermann, Chr. Tamm, E. Peik, A. V. Taichenachev, V. I. Yudin, and P. Głowacki

Phys. Rev. A 85, 033402 (2012)

### Wigner Crystals of 229Th for Optical Excitation of the Nuclear Isomer

C. J. Campbell, A. G. Radnaev, and A. Kuzmich

Phys. Rev. Lett. 106, 223001 (2011)

### Multiply Charged Thorium Crystals for Nuclear Laser Spectroscopy

C. J. Campbell, A. V. Steele, L. R. Churchill, M. V. DePalatis, D. E. Naylor, D. N. Matsukevich, A. Kuzmich, and M. S. Chapman

Phys. Rev. Lett. 102, 233004 (2009)

Electron bridge processes

### Excitation of the isomeric 229mTh nuclear state via an electronic bridge process in 229Th+

S. G. Porsev, V. V. Flambaum, E. Peik, and Chr. Tamm

Phys. Rev. Lett. 105, 182501 (2010)

### Electronic bridge process in Th229+

S. G. Porsev and V. V. Flambaum

Phys. Rev. A 81, 042516 (2010)

### Lasers as a bridge between atomic and nuclear physics

S. Matinyan

Physics Reports 298,199 (1998)

### Nuclear Deexcitation via the Electronic-Bridge Mechanism

D. Kekez, A. Ljubičić, K. Pisk, and B. A. Logan

Phys. Rev. Lett. 55, 1366 (1985)

Internal conversion and related processes

### Band structure and decay channels of thorium-229 low-lying isomeric state for ensemble of thorium atoms adsorbed on calcium fluoride

P. V. Borisyuk, O. S. Vasilyev, A. V. Krasavin, Y. Y. Lebedinskii, V. I. Troyan, and E. V. Tkalya

arXiv:1506.06236 (2015)

### Impact of the electron environment on the lifetime of the 229mTh low-lying isomer

F. F. Karpeshin and M. B. Trzhaskovskaya

Phys. Rev. C 76, 054313 (2007)

### Resonance conversion as a dominant decay mode for the 3.5-eV isomer in 229mTh

F. F. Karpeshin and M. B. Trzhaskovskaya

Physics of Atomic Nuclei 69, 4, 571 (2006)

### Spontaneous emission probability for M1 transition in a dielectric medium: 229mTh (3/2+, 3.5 ± 1.0 eV) decay

E. Tkalya

JETP Lett. 71, 311-313 (2000)

### Decay of the low-energy isomer 229mTh (3/2+, 3.5±1.0eV) in solids (dielectrics and metals): A new scheme of experimental research

E. V. Tkalya, A. N. Zherikhin, and V. I. Zhudov,

Phys. Rev. C 61, 064308 (2000)

### Nonradiative decay of the low-lying nuclear isomer 229m Th(3.5 eV) in a metal

E. V. Tkalya

JETP 70, 371 (1999)

### 3.5-eV isomer of 229mTh: How it can be produced

F.F. Karpeshin, I.M. Band, and M.B. Trzhaskovskaya

Nucl. Phys. A 654, 579-596 (1999)

### Optical pumping 229mTh through NEET as a new effective way of producing nuclear isomers

F.F. Karpeshin, I.M. Band, M.B. Trzhaskovskaya, and M.A. Listengarten

Phys. Lett. B 372, 1-7 (1996)

Uranium-233 recoil experiments

### Determination of the extraction efficiency for U-233 source recoil ions from the MLL buffer-gas stopping cell

L. v. d. Wense, B. Seiferle, M. Laatiaoui, and P. G. Thirolf

Eur. Phys. Jour. A 51, 29 (2015)

### Towards a direct transition energy measurement of the lowest nuclear excitation in 229Th

L. v. d. Wense, P. G. Thirolf, D. Kalb, and M. Laatiaoui

Journal of Instrumentation 8, P03005 (2013)

### Analysis of Parasitic Signals in the Method of Recoil Nuclei Applied to Direct Observation of the 229mTh Isomeric State

P. Bilous and L. Yatsenko

arXiv:1407.2129 (2014)

### Comment on “Observation of the Deexcitation of the 229mTh Nuclear Isomer”

E. Peik and K. Zimmermann

Phys. Rev. Lett. 111, 018901 (2013)

### Observation of the Deexcitation of the 229mTh Nuclear Isomer

X. Zhao, Y. N. Martinez de Escobar, R. Rundberg, E. M. Bond, A. Moody, and D. J. Vieira

Phys. Rev. Lett. 109, 160801 (2012)

### 229Th the Bridge Between Nuclear and Atomic Interactions

J.T. Burke, R.J. Casperson, E.L. Swanberg, and D. Thomas

Report No. LLNL-TR-463538 (2010)

Spectroscopy using synchrotron radiation

### Results of a direct search using synchrotron radiation for the low-energy 229Th nuclear isomeric transition

J. Jeet, Ch. Schneider, S. T. Sullivan, W. G. Rellergert, S. Mirzadeh, A. Cassanho, H. P. Jenssen, E. V. Tkalya, and E. R. Hudson

Phys. Rev. Lett. 114, 253001 (2015)

There is a loosely connected theory paper that recaps previous work on isomer properties and constructs a “favored region” for isomer energy and lifetime.

### Experimental search for the low-energy nuclear transition in Th-229 with undulator radiation

A. Yamaguchi, M. Kolbe, H. Kaser, T. Reichel, A. Gottwald, and E. Peik

New J. Phys. 17, 053053 (2015)

Nuclear data sources

### Nuclear Data Sheets for A = 229

E. Browne and J. K. Tuli

Nuclear Data Sheets 109, 2657 (2008)

Such data sheets, often many 100 pages long, exist for every mass number *A* and are updated on an unregular basis.

PhD theses

### On the direct detection of 229mTh

Lars von der Wense

Ph.D. thesis, LMU Munich (2017)

link

### Coherent Control of Nuclei and X-Rays

Wen-Te Liao

Ph.D. thesis, University of Heidelberg (2013)

link

### Laser excitation of 8-eV electronic states in Th+: a first pillar of the electronic bridge toward excitation of the Th-229 nucleus

Oscar-Andrey Herrera Sancho

Ph.D. thesis, Leibniz Universität Hannover (2012)

link

### Searching for the Decay of ^{229m}Th

Erik Swanberg

Ph.D. thesis, University of California, Berkeley (2012)

link

### Trapping, laser cooling, and spectroscopy of thorium IV

Corey J. Campbell

Ph.D. thesis, Georgia Institute of Technology (2011)

link

### Experiments Towards Optical Nuclear Spectroscopy of Thorium-229

Kai Zimmermann

Ph.D. thesis, Leibniz Universität Hannover (2010)

link