arXiv subjects

Jiangfeng Zhou

Publications and source records attributed to Jiangfeng Zhou.

At least 19 recordsLinked to original sources

arXiv2024

A novel nuclear recoil calibration for liquid noble gas detectors

According to many dark matter models, a potential signal registered in a detector would feature a single-scattering nuclear recoil (NR). So, it is crucial to calibrate the detector's response to NR events. The conventional calibrations implement $\sim$ keV to MeV neutrons, which can be produced by an accelerator, a neutron generator, or a radioactive source. Although the calibrating methods have been widely employed, they could be improved in several ways: (a) the incident neutron energy should be more monoenergetic, (b) the calibrating NR energy should line up with the region of interest (ROI) of the experiment, and (c) the intensity of the beam should be appropriate. In the paper, we introduce a novel NR calibration method for liquid helium detectors, in which a helium beam ($α$ particles) will be implemented to calibrate the detectors. The helium beam can (i) be tuned precisely to have a jitter of $\lesssim $ 4\% (the $α$ beam's kinetic energy is equivalent to the recoil energy in the conventional calibrations with fast neutrons); (ii) have an energy between $\sim$ 100 eV and tens of keV; and (iii) provide a tunable flux from nA to 100 $μ$A, which presents convenience in beam pipe configuration to obtain a $\sim$ 100 Hz events rate so that the events pileup would be ignorable.

physics.ins-det↗

arXiv2023

Characterization of FBK NUV-HD-Cryo SiPMs near LHe temperature

Five FBK ``NUV-HD-Cryo'' SiPMs have been characterized at 7 K and 10 K, with 405 nm and 530 nm LED light, respectively. The dark count rate (DCR) was measured to be $\sim$ 1 Hz for the $\sim$ 100 mm$^2$-size SiPMs, or 0.01 Hz/mm$^2$, which is $\sim$ 7 orders lower than the DCR at room temperature (RT). Given the very low DCR at these cryogenic temperatures, we measured the SiPMs' I-V curves with such a method: illuminated the SiPMs with weak light, which differs from the conventional measurements at RT. Then, we measured the photo-detection efficiency (PDE), after-pulse (AP), and cross-talk (CT) with a bias voltage ranging from overvoltage (OV) 5 to 11 V. At the OV interval (5 to 11 V), the PDE was between 20\% - 45\%, and the AP and CT were both between $\sim$ 5\% and $\sim$ 20\%. With an OV higher than 10 V, the PDE would be $\ge$ 40\%, and the AP and CT are $\sim$ 20\%. Combining all of the measurements, we are confident that the SiPMs can be equipped as the photosensors on liquid helium detectors, including but not limited to the time projection chambers, which we have proposed in hunting for low-mass dark matter directly and beyond.

physics.ins-det↗

arXiv2023

Search for ER and/or NR-like dark matter signals with the especially low background liquid helium TPCs

In the Dark Matter (DM) direct detection community, the absence of convincing signals has become a "new normal" for decades. Among other possibilities, the "new normal" might indicate that DM-matter interactions could generate not only the hypothetical NR (Nuclear Recoil) events but also the ER (Electron Recoil) ones, which have often been tagged as backgrounds historically. Further, we argue that ER and NR-like DM signals could co-exist in a DM detector's same dataset. So in total, there would be three scenarios we can search for DM signals: (i) ER excess only, (ii) NR excess only, and (iii) ER and NR excesses combined. To effectively identify any possible DM signal under the three scenarios, a DM detector should (a) have the minimum ER and NR backgrounds and (b) be capable of discriminating ER events from NR ones. Accordingly, we introduce the newly established project, ALETHEIA, which implements liquid helium-filled TPCs (Time Projection Chambers) in hunting for DM. Thanks to the nearly single-digit number of ER and NR backgrounds on 1 ton*yr exposure, presumably, the ALETHEIA detectors could identify any form of DM-induced excess in its ROI (Research Of Interest). As far as we know, ALETHEIA is the first DM direct detection experiment claiming such an inclusive search; conventional detectors search DM mainly on the "ER excess only" and/or the "NR excess only" channel, not the "ER and NR excesses combined" channel.

astro-ph.IM↗

arXiv2023

Conceptual design and progress of transmitting $\sim$ MV DC HV into 4 K LHe detectors

A dual-phase TPC (Time Projection Chamber) is more advanced in characterizing an event than a single-phase one because it can, in principle, reconstruct the 3D (X-Y-Z) image of the event, while a single-phase detector can only show a 2D (X-Y) picture. As a result, more enriched physics is expected for a dual-phase detector than a single-phase one. However, to build such a detector, DC HV (High Voltage) must be delivered into the chamber (to have a static electric field), which is a challenging task, especially for an LHe detector due to the extremely low temperature, $\sim$ 4 K, and the very high voltage, $\sim$ MV (Million Volts). This article introduces a convincing design for transmitting $\sim$ MV DC into a 4 K LHe detector. We also report the progress of manufacturing a 100 kV DC feedthrough capable of working at 4 K. Surprisingly, we realized that the technology we developed here might be a valuable reference to the scientists and engineers aiming to build residential bases on the Moon or Mars.

physics.ins-det↗

arXiv2022

ALETHEIA: Hunting for Low-mass Dark Matter with Liquid Helium TPCs

Dark Matter (DM) is one of the most critical questions to be understood and answered in fundamental physics today. Observations with varied astronomical and cosmological technologies strongly indicated that DM exists in the Universe, the Milky Way, and the Solar System. Nevertheless, understanding DM under the language of elementary physics is still in progress. DM direct detection tests the interactive cross-section between galactic DM particles and an underground detector's nucleons. Although Weakly Interactive Massive Particles (WIMPs) are the most discussed DM candidates, the null-WIMPs conclusion has been consistently addressed by the most convincing experiments in the field. Relatively, the low-mass WIMPs region ($\sim$ 10 MeV/c$^2$ - 10 GeV/c$^2$) has not been fully exploited compared to high-mass WIMPs ($\sim$ 10 GeV/c$^2$ - 10 TeV/c$^2$). The ALETHEIA (A Liquid hElium Time projection cHambEr In dArk matter) experiment aims to hunt for low-mass WIMPs with liquid helium-filled TPCs (Time Projection Chambers). In this paper, we go through the physics motivation of the project, the detector's design, the R\&D plan, and the progress we have made since the project has been launched in the summer of 2020.

astro-ph.IM↗

arXiv2022

Coating $μ$m TPB on a cylindrical detector and studying the sample films being cooled to LN and LHe temperatures

ALETHEIA is a newly established dark matter direct detection project that aims at hunting for low-mass WIMPs. TPB is widely implemented in liquid helium and argon experiments to shift VUV photons to visible light. We first report that we have successfully coated $\sim 3 ~μ$m TPB on the inner walls of a 10-cm cylindrical PTFE detector; we split the coating process into two steps to have all of the surfaces being coated with the same thickness; three independent methods were applied to figure out the thickness of the TPB coating layers, and consistent results were obtained. Second, with an SEM machine, we scanned the surface of TPB coating sample films exposed to different cryogenic temperatures. The first group of sample layers were immersed into a liquid nitrogen dewar for forty hours, the second group samples were cooled to 4.5 K for three hours, and the third group stayed at room temperature after coating. The SEM-scanned images of the sample films barely show any noticeable difference.

physics.ins-det↗

arXiv2022

Introduction to a low-mass dark matter project, ALETHEIA: A Liquid hElium Time projection cHambEr In dArk matter

Dark Matter (DM) is one of the most critical questions to be understood and answered in fundamental physics today. Plenty of astronomical and cosmological observations have already pinned down that DM exists in the Universe, the Milky Way, and the Solar System. However, understanding DM with the language of elementary physics is still in progress. DM direct detection tests the interactive cross-section between galactic DM particles and an underground detector's nucleons. WIMPs is the most discussed DM candidate. After decades of hunting, a convincing WIMPs signal is still at large. Relatively, the low-mass WIMPs region ($\sim$ 10 MeV/c$^2$ - 10 GeV/c$^2$) has not been fully exploited compared to high-mass WIMPs ($\sim$ 10 GeV/c$^2$ - 10 TeV/c$^2$). By filling the arguably cleanest bulk material, LHe, into the arguably most competitive detector in the field, TPCs, ALETHEIA is supposed to achieve an extremely low-level background; therefore, to help answer one of the most pressing physical questions today: the nature of DM. In this paper, we briefly go through the physics motivation of low-mass DM, the ALETHEIA detector's design, possible analysis channels available for DM searches, and the progress we have made since the project launched in the summer of 2020.

astro-ph.IM↗

arXiv2021

A low-mass dark matter project, ALETHEIA: A Liquid hElium Time projection cHambEr In dArk matter

Dark Matter (DM) is one of the most critical questions to be understood and answered in fundamental physics today. Observations with varied astronomical and cosmological technologies already pinned down that DM exists in the Universe, the Milky Way, and the Solar System. However, the understanding of DM under the language of elementary physics is still in progress. DM direct detection aims to test the interactive cross-section between galactic DM particles and an underground detector's nucleons. Although Weakly Interactive Massive Particles (WIMPs) is the most discussed DM candidate, the null-WIMPs conclusion has been consistently addressed by most convincing experiments in the field. The low-mass WIMPs region (100s MeV/c$^2$ - 10 GeV/c$^2$) has not been fully exploited comparing to high-mass WIMPs (10 GeV/c$^2$ - 1 TeV/c$^2$) experiments which implement liquid xenon or argon TPCs (Time Projection Chambers). The ALETHEIA experiment aims to hunt for low-mass WIMPs with liquid helium-filled TPCs. In this paper, we go through the physics motivation of low-mass DM, the ALETHEIA detector's design, a series of R&D programs that should be launched to address a liquid helium TPC's functionality, and possible analysis channels available for DM searches. We designed and homemade a 30 g liquid helium prototype detector at CIAE. In Summer 2021, the detector was cooled down to 4.5 K successfully. The detector's dark current is less than ten pA for an external voltage up to 17 kV/cm when filled with vacuum, 1 atm nitrogen gas, and liquid nitrogen.

astro-ph.IM↗

arXiv2017

Giant THz surface plasmon polariton induced by high-index dielectric metasurface

We use computational approaches to explore the role of a high-refractive-index dielectric TiO2 grating with deep subwavelength thickness on InSb as a tunable coupler for THz surface plasmons. We find a series of resonances as the grating couples a normally-incident THz wave to standing surface plasmon waves on both thin and thick InSb layers. In a marked contrast with previously-explored metallic gratings, we observe the emergence of a much stronger additional resonance. The mechanism of this giant plasmonic resonance is well interpreted by the dispersion of surface plasmon excited in the air\TiO2\InSb trilayer system. We demonstrate that both the frequency and the intensity of the giant resonance can be tuned by varying dielectric grating parameters, providing more flexible tunability than metallic gratings. The phase and amplitude of the normally-incident THz wave are spatially modulated by the dielectric grating to optimize the surface plasmon excitation. The giant surface plasmon resonance gives rise to strong enhancement of the electric field above the grating structure, which can be useful in sensing and spectroscopy applications.

physics.app-ph↗

arXiv2017

Low-loss Broadband Negative Refractive Index due to Nonresonant 2D Helical Chiral Metamaterial

We demonstrated a 2D helical chiral metamaterial that exhibits broadband strong optical activity resulting nonresonant Drude-like response. The strong chirality leads to broadband negative refractive index with high figure of merit (>90) and extremely low loss (<2% per layer). The optical activity are insensitive to the angles of incident electromagnetic waves, thereby enabling more flexibility in polarization manipulation applicaitons.

physics.optics↗

arXiv2017

Metamaterial Perfect Absorber Analyzed by a Meta-cavity Model Consisting of Multilayer Metasurfaces

We demonstrate that the metamaterial perfect absorber behaves as a meta-cavity bounded between a resonant metasurface and a metallic thin-film reflector. The perfect absorption is achieved by the Fabry-Perot cavity resonance via multiple reflections between the "quasi-open" boundary of resonator and the "closed" boundary of reflector. The characteristic features including angle independence, ultra-thin thickness and strong field localization can be well explained by this model. With this model, metamaterial perfect absorber can be redefined as a meta-cavity exhibiting high Q-factor, strong field enhancement and extremely high photonic density of states, thereby promising novel applications for high performance sensor, infrared photodetector and cavity quantum electrodynamics devices.

physics.optics↗

arXiv2017

A Highly Efficient Polarization-Independent Metamaterial-Based RF Energy-Harvesting Rectenna for Low-Power Applications

A highly-efficient multi-resonant RF energy-harvesting rectenna based on a metamaterial perfect absorber featuring closely-spaced polarization-independent absorption modes is presented. Its effective area is larger than its physical area, and so efficiencies of 230% and 130% are measured at power densities of 10 uW/cm2 and 1 uW/cm2 respectively, for a linear absorption mode at 0.75 GHz. The rectenna exhibits a broad polarization-independent region between 1.4 GHz and 1.7 GHz with maximum efficiencies of 167% and 36% for those same power densities. Additionally, by adjustment of the distance between the rectenna and a reflecting ground plane, the absorption frequency can be adjusted to a limited extent within the polarization-independent region. Lastly, the rectenna should be capable of delivering 100 uW of power to a device located within 50 m of a cell-phone tower under ideal conditions.

physics.app-ph↗

arXiv2017

A Metamaterial-inspired Approach to RF Energy Harvesting

We demonstrate an RF energy harvesting rectenna design based on a metamaterial perfect absorber (MPA). With the embedded Schottky diodes, the rectenna converts captured RF waves to DC power. The Fabry-Perot (FP) cavity resonance of the MPA greatly improves the amount of energy captured. Furthermore, the FP resonance exhibits a high Q-factor and significantly increases the voltage across the Schottky diodes, which improves the rectification efficiency, particularly at low power. This leads to factor of 16 improvement of RF-DC conversion efficiency at ambient intensity level.

physics.app-ph↗

arXiv2017

Tunable Optical Bistability and Optical Switching by Nonlinear Metamaterials

We demonstrate a nonlinear metamaterial in microwave frequency regime with hysteresis effect and bistable states, which can be utilized as a remotely controllable micro second switching device. A varactor loaded split-ring resonator (SRR) design which exhibits power and frequency dependent broadband tunability of the resonance frequency for an external control signal is used. More importantly, the SRR shows bistability with distinct transmission levels. The transition between bi-states is controlled by impulses of an external pump signal. Furthermore, we experimentally demonstrate that transition rate is in the order of microseconds by using a varactor loaded double split-ring resonator (DSRR) design composed of two concentric rings.

physics.app-ph↗

arXiv2017

Enhanced Second-harmonic Generation Using Nonlinear Metamaterials

We demonstrate a nonlinear metamaterial which enhance higher order harmonics in microwave frequency regime. Nonlinearity in the structure is introduced by adding a varactor diode in the common slit of the double split ring resonator (DSRR) design. By engineering the structure such that inner ring resonance frequency of the DSRR is twice as the outer ring resonance frequency, we have demonstrated that the second harmonic of the outer ring can be enhanced significantly. By comparing with a single ring (SRR) unit cell structure, DSRR has an enhancement factor of 70. Furthermore, we elucidate that the second harmonic signals generated by two identical double split rings interfere and we can use its constructive interference positions to construct an array of DSRRs that gives a maximum second harmonic signal with phase matching condition. When the phase matching condition occurs the enhancement factor of an array is more than the contribution of individual unit cells which proves that the enhancement is due to not only constructive interference of the second harmonic generated by individual unit cells but also due to cavity mechanism occurred in the array structure.

physics.app-ph↗

arXiv2016

Broadband angle- and permittivity-insensitive nondispersive optical activity based on chiral metamaterials

Because of the strong inherent resonances, the giant optical activity obtained via chiral metamaterials generally suffers from high dispersion, which has been a big stumbling block to broadband applications. In this paper, we propose a type of chiral metamaterial consisting of interconnected metal helix structures with four-fold symmetry, which exhibits nonresonant Drude-like response and can therefore avoid the highly dispersive optical activity resulting from resonances. It shows that the well-designed chiral metamaterial can achieve nondispersive and pure optical activity with high transmittance in a broadband frequency range. And the optical activity of multi-layer chiral metamaterials is proportional to the layer numbers of single-layer chiral metamaterial. Most remarkably, the broadband behaviors of nondispersive optical activity and high transmission are insensitive to the incident angles of electromagnetic waves and permittivity of dielectric substrate, thereby enabling more flexibility in polarization manipulation.

physics.optics↗

arXiv2016

Thin InSb layers with metallic gratings: a novel platform for spectrally-selective THz plasmonic sensing

We present a computational study of terahertz optical properties of a grating-coupled plasmonic structure based on micrometer-thin InSb layers. We find two strong absorption resonances that we interpret as standing surface plasmon modes and investigate their dispersion relations, dependence on InSb thickness, and the spatial distribution of the electric field. The observed surface plasmon modes are well described by a simple theory of the air/InSb/air trilayer. The plasmonic response of the grating/InSb structure is highly sensitive to the dielectric environment and the presence of an analyte (e.g., lactose) at the InSb interface, which is promising for terahertz plasmonic sensor applications. We determine the sensor sensitivity to be 7200 nm per refractive index unit (or 0.06 THz per refractive index unit). The lower surface plasmon mode also exhibits a splitting when tuned in resonance with the vibrational mode of lactose at 1.37 THz. We propose that such interaction between surface plasmon and vibrational modes can be used as the basis for a new sensing modality that allows the detection of terahertz vibrational fingerprints of an analyte.

cond-mat.mes-hall↗

arXiv2011

Application of metasurface description for multilayered metamaterials and an alternative theory for metamaterial perfect absorber

We analyze single and multilayered metamaterials by modeling each layer as a metasurface with effective surface electric and magnetic susceptibility derived through a thin film approximation. Employing a transfer matrix method, these metasurfaces can be assembled into multilayered metamaterials to realize certain functionalities. We demonstrate numerically that this approach provides an alternative interpretation of metamaterial-based perfect absorption, showing that the underlying mechanism is a modified Fabry-Perot resonance. This method provides a general approach applicable for decoupled or weakly coupled multilayered metamaterials.

physics.optics↗