Electrostatic focusing of cold and heavy molecules for the ACME electron EDM search

Wu, Xing; Hu, P; Han, Zhuo Rachel; Ang, Daniel; Meisenhelder, Cole; Gabrielse, Gerald; Doyle, John M.; DeMille, D.

doi:10.1088/1367-2630/ac8014

Cited by 9 publications

(3 citation statements)

References 34 publications

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“…The gas was cooled down by 17 K neon buffer gas, forming a cryogenic molecular beam mostly in the ground (X ) electronic state [32]. The molecules in the beam were then excited to the Q state using Stimulated Raman Adiabatic Passage (STIRAP) via X-C-Q transitions [33] and were collimated by an electrostatic molecular lens to the readout region downstream [34]. The molecules in the Q state were resonantly excited to the I state by a 746 nm continuous-wave laser (M Squared SolsTis), which decays quickly (lifetime 115 ± 4 ns [35]) to the ground state X, emitting 512 nm photons.…”

Section: Molecular Fluorescence Measurementmentioning

confidence: 99%

High-sensitivity low-noise photodetector using large-area silicon photomultiplier

Masuda¹,

Hiramoto²,

Ang³

et al. 2022

Preprint

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The application of silicon photomultiplier (SiPM) technology for weak-light detection at a single photon level has expanded thanks to its better photon detection efficiency in comparison to a conventional photomultiplier tube (PMT). SiPMs with large detection area have recently become commercially available, enabling applications where the photon flux is low both temporarily and spatially. On the other hand, several drawbacks exist in the usage of SiPMs such as a higher dark count rate, many readout channels, slow response time, and optical crosstalk; therefore, users need to carefully consider the trade-offs. This work presents a SiPM-embedded compact largearea photon detection module. Various techniques are adopted to overcome the disadvantages of SiPMs so that it can be generally utilized as an upgrade from a PMT. A simple cooling component and recently developed optical crosstalk suppression method are adopted to reduce the noise which is more serious for larger-area SiPMs. A dedicated readout circuit increases the response frequency and reduces the number of readout channels. We favorably compare this design with a conventional PMT and obtain both higher photon detection efficiency and larger-area acceptance.

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Section: Molecular Fluorescence Measurementmentioning

confidence: 99%

High-sensitivity low-noise photodetector using large-area silicon photomultiplier

Masuda¹,

Hiramoto²,

Ang³

et al. 2022

Preprint

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“…The hexapole lens was developed for BaF molecules in the first excited rotational level (N = 1) of the electronic and vibrational ground state and has also been tested with molecules in the second excited rotational state (N = 2) state, that may be used as an upgrade to the experiment in the future. In a related study, Wu et al used a hexapole lens to enhance the molecular flux of ThO molecules for the ACME experiment [15].…”

Section: Introductionmentioning

confidence: 99%

Manipulating a beam of barium fluoride molecules using an electrostatic hexapole

Touwen,

van Hofslot,

Qualm

et al. 2024

New J. Phys.

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An electrostatic hexapole lens is used to manipulate the transverse properties of a beam of barium fluoride molecules from a cryogenic buffer gas source. The spatial distribution of the beam is measured by recording state-selective laser-induced fluorescence on an emccd camera, providing insight into the intensity and transverse position spread of the molecular beam. Although the high mass and unfavorable Stark shift of barium fluoride pose a considerable challenge, the number of molecules in the low-field seeking component of the N = 1 state that pass a 4 mm diameter aperture 712 mm behind the source is increased by a factor of 12. Furthermore, it is demonstrated that the molecular beam can be displaced by up to ±5 mm by moving the hexapole lens. Our measurements agree well with numerical trajectory simulations. We discuss how electrostatic lenses may be used to increase the sensitivity of beam experiments such as the search for the electric dipole moment of the electron.

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“…Figure 1 shows the apparatus for ACME III. A cryogenic buffer-gas beam source generates a cold ThO beam, and hexapole electrodes focus that beam into the interaction region increasing the number of detected molecules [5]. At the entrance of the spin precession region, molecules are optically driven into the H state for the eEDM measurement, where the unpaired electron spins precess in combined electric and magnetic fields.…”

Section: Introductionmentioning

confidence: 99%

SiPM module for the ACME III electron EDM search

Hiramoto¹,

Masuda²,

Ang³

et al. 2022

Preprint

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This report shows the design and the performance of a large area Silicon Photomultiplier (SiPM) module developed detection of fluorescent light emitted from a ∼10cm scale volume. The module was optimized for the planned ACME III electron electric dipole moment (eEDM) search, which will be a powerful probe for the existence of physics beyond the Standard Model of particle physics. The ACME experiment searched for the eEDM with the world's highest sensitivity using cold ThO polar molecules (ACME II [1]). In ACME III, SiPMs will be used for detection of fluorescent photons (the fundamental signal of the experiment) instead of PMTs, which were used in the previous measurement. We have developed an optimized SiPM module, based on a 16-channel SiPM array. Key operational parameters are characterized, including gain and noise. The SiPM dark count rate, background light sensitivity, and optical crosstalk are found to all be well suppressed and more than sufficient for the ACME III application.

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Electrostatic focusing of cold and heavy molecules for the ACME electron EDM search

Cited by 9 publications

References 34 publications

High-sensitivity low-noise photodetector using large-area silicon photomultiplier

High-sensitivity low-noise photodetector using large-area silicon photomultiplier

Manipulating a beam of barium fluoride molecules using an electrostatic hexapole

SiPM module for the ACME III electron EDM search

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