Search

Axions and axion‐like particles are hypothetical particles predicted in extensions of the standard model and are promising cold dark matter candidates. The Any Light Particle Search (ALPS II) experiment is a light‐shining‐through‐the‐wall experiment that aims to produce these particles from a strong light source and magnetic field and subsequently detect them through a reconversion into photons. With an expected rate ≈1 photon per day, a sensitive detection scheme needs to be employed and characterized. One foreseen detector is based on a transition edge sensor (TES). Here, the machine and deep learning algorithms for the rejection of background events recorded with the TES are investigated. A first application of convolutional neural networks to classify time series data measured with the TES is also presented. [ABSTRACT FROM AUTHOR]

Transition Edge Sensors (TESs) have found widespread application in fundamental studies due to their low background rate, high efficiency, and excellent energy resolution. This makes them suitable candidates for ALPS II, which investigates the existence of new particles (axions and axion-like-particles) which couple very weakly to photons. ALPS II anticipates an extremely low signal rate < 10 - 5 cps (amounting to ∼ 1–2 photons a day). The detection of these low energy (∼ 1 eV, 1064 nm) photons with a high energy resolution is necessary for ALPS II. We show that with our TES setup, we can analyze the TES pulses with different methods such as pulse fitting and Principal Component Analysis (PCA). These achieve (using the standard deviation) an energy resolution ( Δ E / E ) down to ∼ 8 % . The pulse analysis, with a chosen fitting approach, assists also in achieving a very low dark count rate O 10 - 6 cps for 1064 nm photon signal searches in the TES. [ABSTRACT FROM AUTHOR]

A finite axion–nucleon coupling, nearly unavoidable for QCD axions, leads to the production of axions via the thermal excitation and subsequent de-excitation of 57 Fe isotopes in the sun. We revise the solar bound on this flux adopting the up to date emission rate, and investigate the sensitivity of the proposed International Axion Observatory IAXO and its intermediate stage BabyIAXO to detect these axions. We compare different realistic experimental options and discuss the model dependence of the signal. Already BabyIAXO has sensitivity far beyond previous solar axion searches via the nucleon coupling and IAXO can improve on this by more than an order of magnitude. [ABSTRACT FROM AUTHOR]

Four decades after its prediction, the axion remains the most compelling solution to the strong- CP problem and a well-motivated dark matter candidate, inspiring a host of elegant and ultrasensitive experiments based on axion-photon mixing. This article reviews the experimental situation on several fronts. The microwave cavity experiment is making excellent progress in the search for dark matter axions in the μeV range and may plausibly be extended up to 100 μeV. Within the past several years, however, researchers have realized that axions are pervasive throughout string theories, but with masses that fall naturally in the neV range, for which an NMR-based search is under development. Both searches for axions emitted from the Sun's burning core and purely laboratory experiments based on photon regeneration have recently made great progress, with ambitious projects proposed for the coming decade. Each of these campaigns has pushed the state of the art in technology, enabling large gains in sensitivity and mass reach. Furthermore, each modality has been exploited in order to search for more generalized axion-like particles, which we also discuss in this review. We are hopeful, even optimistic, that the next review of the subject will concern the discovery of the axion, its properties, and its exploitation as a probe of early universe cosmology and structure formation. [ABSTRACT FROM AUTHOR]