LATEX TikZposter Collective effects in driving the 229Th nuclear transition Brenden S. Nickerson & Adriana P´alﬀy Max-Planck-Institut f¨ur Kernphysik Collective effects in driving the 229Th nuclear transition Brenden S. Nickerson & Adriana P´alﬀy Max-Planck-Institut f¨ur Kernphysik Abstract The high accuracy of atomic clocks lies behind the success of the Global Positioning System, which requires synchronization of orbiting satellites for triangulation. More precise clocks are desirable for challenging Einstein’s theory of general relativity or for Earth-observation satellites tracking the sea level, and would generally allow to push the bounds of observable physics. The unique lowest transition in the 229Th nucleus with frequency in the vacuum ultraviolet (VUV) range and very narrow line-width promises enhanced precision and amazing stability [1]. This level is a nuclear isomeric state at approx. 7.8 eV that can be reached by VUV lasers. A very exact measurement of the isomeric transition energy has been elusive, with the ﬁrst conﬁrmation of the level decay coming only recently [2]. Here we investigate the possibility to exploit collective eﬀects in order to design a more sensitive nuclear excitation scheme in the process of scattering of light through a Th-doped crystal. The crystalline environment enforces the M¨ossbauer regime, allowing for recoil-free emission and absorption and collective behaviour [3]. By taking advantage of such eﬀects we aim to resolve not only the transition energy but provide a clear signature of the excitation. Introduction to 229Th ⇒The isotope 229Th bridges atomic and nuclear physics with its unique long-lived nuclear excited state with the energy of 7.8 eV [4] ⇒The advantages of this nuclear transition are its very narrow width, the stability to external perturbations and an accessible frequency within the VUV region, rendering it a candidate for a nuclear clock system (Th Standard at 10−19 [5]). ⇒Measurement of the isomeric transition energy has been elusive with the ﬁrst direct measurement coming only recently [2]. 5/2+ 7/2+ 9.2+ 3/2+ 5/2+ 7/2+ 0 42.43 97.13 71.82 29.19 0.0078 42.43 54.70 25.31 29.39 42.63 29.18 E [keV] 3 6 9 12 15 18 21 24 27 30 0 0.2 0.4 0.6 0.8 1 ⇡ 3⇡ 5⇡ 7⇡ 9⇡ ⌦t ⇢ee 3 6 9 12 15 18 21 24 27 30 0 0.2 0.4 0.6 0.8 1 ⇡ 3⇡ 5⇡ 7⇡ 9⇡ ⌦t ⇢ee 0 0.5 1 1.5 2 2.5 3 3.5 4 ·10−7 10−2 10−4 10−6 10−8 10−10 10−12 t ⌦2/⌦2 0 ∂tˆρ = 1 i¯h[ ˆH, ˆρ] + ˆρr 1 c∂tΩ+ ∂zΩ= iηρeg Ωij = ⟨i|d|j⟩· E ¯h mg + 1 2 −1 2 me −3 2 −1 2 + 1 2 + 3 2 =14.4 keV 57Fe Ig = 1 2 Ie = 3 2 ⌦ Coherent Driving of Thorium Nuclei ⇒Th doped in CaF2 crystal enforces the M¨ossbauer regime, where CaF2 is trans- parent at the energy required to drive the Th isomeric transition. ⇒Based on the polarity of the laser chosen we can probe diﬀerent transitions. Seen to the right is the quadrupole level splitting of 229Th in 229Th : CaF2 along with the two and three level systems investigated in [3]. ⇒Driving the two level system results in an exponentially decaying intensity proﬁle (a) which is sensitive to ∆on the order 107Γ (1 kHz) but does not possess a unique spectra. ⇒The addition of a coupling laser allows us to drive a second transition which introduces characteristic beating signature of the isomeric excitation (b). Fitting experimental data can determine ∆and therefore the 229gTh →229m Th transition frequency to a precision of 105Γ (10 Hz). Outlook ⇒With NFS in mind, we can change the level scheme of interest by looking at diﬀerent host crystals and structured samples. ⇒Applying a magnetic ﬁeld can give the opportunity to provide an signature that is even more sensitive the detuning parameters. M¨ossbauer Nuclei, NFS and Transition Energy ⇒229Th doped in a VUV transparent crystal enforces the M¨ossbauer regime, al- lowing for recoil free emission when driving the nuclear transition. ⇒Nuclear Forward Scattering (NFS) has been used successfully to identify nuclear transition energies in the well studied 57Fe as well as a variety