The Large High Altitude Air Shower Observatory (LHAASO) Science White Paper

The Large High Altitude Air Shower Observatory (LHAASO) project is a new generation multi-component instrument, to be built at 4410 meters of altitude in the Sichuan province of China, with the aim to study with unprecedented sensitivity the spec trum, the composition and the anisotropy of cosmic rays in the energy range between 10$^{12}$ and 10$^{18}$ eV, as well as to act simultaneously as a wide aperture (one stereoradiant), continuously-operated gamma ray telescope in the energy range between 10$^{11}$ and $10^{15}$ eV. The experiment will be able of continuously surveying the TeV sky for steady and transient sources from 100 GeV to 1 PeV, t hus opening for the first time the 100-1000 TeV range to the direct observations of the high energy cosmic ray sources. In addition, the different observables (electronic, muonic and Cherenkov/fluorescence components) that will be measured in LHAASO will allow to investigate origin, acceleration and propagation of the radiation through a measurement of energy spec trum, elemental composition and anisotropy with unprecedented resolution. The remarkable sensitivity of LHAASO in cosmic rays physics and gamma astronomy would play a key-role in the comprehensive general program to explore the High Energy Universe. LHAASO will allow important studies of fundamental physics (such as indirect dark matter search, Lorentz invariance violation, quantum gravity) and solar and heliospheric physics. In this document we introduce the concept of LHAASO and the main science goals, providing an overview of the project.Comment: This document is a collaborative effort, 185 pages, 110 figure

Fabrication of Zn_<i>x</i>Cd_1–<i>x</i>Se Nanocrystal-Sensitized TiO₂ Nanotube Arrays and Their Photoelectrochemical Properties

Zn_<i>x</i>Cd_1–<i>x</i>Se (0 ≤<i> x</i> ≤ 1) nanocrystals were pulse electrodeposited onto the surface of anatase TiO₂ nanotube arrays for the first time. The pulse-electrodeposition duty cycle plays a determinative role during the nuclei formation and growth process of the Zn_<i>x</i>Cd_1–<i>x</i>Se nanocrystals. The composite Zn_<i>x</i>Cd_1–<i>x</i>Se/TiO₂ nanotube arrays exhibit high absorption in the visible light region due to the narrow band gap of Zn_<i>x</i>Cd_1–<i>x</i>Se and demonstrate a sensitive photoelectrochemical response under visible light illumination with an optimal response achieved for Zn_0.8Cd_0.2Se/TiO₂ electrodes. In photoelectrochemical testing, 9-anthracene carboxylic acid acts as a hole donor resulting in a decrease of the measured photocurrent response. In contrast, 2-anthramine acts as an electron donor, resulting in an increase of the photocurrent response

Direct Electrochemistry and Glucose Biosensing of Glucose Oxidase-Gold Nanoparticles Composite Synthesized by Enzyme Method

将NaAuCl4、葡萄糖氧化酶（GOx）和葡萄糖混合，借一步酶促反应制得吸附GOx的金纳米颗粒（AuNPs），再通过滴干修饰法研制了Nafion/GOx-AuNPs修饰的玻碳（GC）电极，并考察了该酶电极上GOx的直接电化学和生物传感性能. 这种酶法合成的GOx-AuNPs复合物有良好的酶直接电化学活性，也保持了GOx的生物活性，似可归因于酶法合成的纳米金更接近酶氧化还原活性中心的缘故. 该酶电极在-0.4 V（vs. SCE）电位下，其稳态电流下降与葡萄糖浓度（0.5 4 mmol&middot;L-1）成正比，检测下限0.2 mol&middot;L-1.Glucose oxidase (GOx)-gold nanoparticles (AuNPs) composite was synthesized by the one-pot enzyme reaction in the mixture solution of NaAuCl4, GOx and glucose, and a Nafion/GOx-AuNPs/glassy carbon electrode was fabricated by the cast-coating method to examine the direct electrochemistry of GOx and the biosensing performance on this electrode. Such a GOx-AuNPs composite showed good direct-electrochemistry activity and bioactivity of GOx, probably because the enzyme-mediated AuNPs are close to the redox active centers of GOx. This enzyme electrode exhibited a linear amperometric response to glucose concentration (0.54 mmol&middot;L-1) at -0.4 V (vs. SCE), and a detection limit of 0.2 mol&middot;L-1 was obtained.国家自然科学基金项目（No. 21175042，No. 21075036）资助作者联系地址：1. 湖南师范大学 化学化工学院，化学生物学及中药分析教育部重点实验室，湖南 长沙 410081； 2. 浙江大学生物系统工程与食品科学学院，浙江 杭州 310029Author's Address: 1. Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research Ministry of Education, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China; 2. College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310029, China通讯作者E-mail：[email protected]

Measurements of D-D fusion neutrons generated in nanowire array laser plasma using Timepix3 detector

Pulse width modulation (PWM) is widely used in different applications. PWM transforms the information in the amplitude of a bounded input signal into the pulse width output signal without suffering from quantization noise. The frequency of the output signal is usually constant. In this paper, the new PWM system with frequency changing (PWMFM) is described. In such PWMFM the pulse width and also the carrier frequency are changed. Therefore, two independent pieces of information can be simultaneously transmitted over one channel; hence PWM and frequency modulation (FM) are simultaneously used. But such system needs 2 demodulators, one for PWM and the second for FM. PWMFM can be used in the following applications: LED light intensity control via PWM and several LED block switching by FM PWMFM is highly useful in motor speed control applications by PWM and direction of rotation with FM. PWMFM can be used also in a class-D audio amplifier for power control, e.g. coarse by means of FM and fine by PWM. PWMFM can be used for the simultaneous transmission of two independent information between all, mutual combinations of analog and digital circuits. The analog and digital circuits for modulation and demodulation of PWMF signal are described and measuring results are presented in this work