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Particle Detection
Published in Walter Fox Smith, Experimental Physics, 2020
For a first “look” at particles, it would be instructive to construct a cloud chamber. A cloud chamber allows for an observation of particle tracks in the clouds as high energy particles pass through. That is, the ionizing particles remove electrons from the molecules in the cloud. These ions become nucleation sites for the surrounding molecules, which are attracted to ions and condense to form droplets. As ionizing radiation moves through the cloud, it leaves a trail of these droplets. Cosmic rays (high energy muons, which are more massive cousins of electrons) that are continuously streaming to Earth can be observed at a fairly low rate. Putting a beta or alpha source in the cloud chamber shows much more activity. Instructions for building a cloud chamber can be found at [20].
Global Environmental System Enfolding Built-Environmental Systems
Published in Masanori Shukuya, Bio-Climatology for Built Environment, 2019
Figure 12.3 also shows that the change in cloud-cover fraction observed from satellites is consistent with the change in the cosmic-ray count within the atmosphere (Svensmark and Friis-Christensen 1997, Calder 1997). The cloud-forming mechanism in relation to the availability of galactic cosmic rays penetrating into the terrestrial atmosphere has gradually been clarified by Svensmark et al. (Svensmark and Calder 2007, Svensmark et al. 2013). The key phenomena of cloud formation is what can be seen in a cloud chamber originally invented by C. T. R. Wilson (1869–1959) (Longair 2014), that is, the generation of cloud condensation nuclei, on which water vapour condenses and grows into droplets of water, is basically due to the ionization of supersaturated moist air, for which intense subatomic particles have to pierce through and thereby generate the shower of secondary particles such as pions, muons, electrons, and photons.
B
Published in Splinter Robert, Illustrated Encyclopedia of Applied and Engineering Physics, 2017
[general, nuclear] A sealed vessel designed to provide a visual impression of the trajectory of an electrically charged particle. The chamber is either filled with a saturated gas (i.e., cloud chamber) or superheated transparent liquid. On the passage of the ion, the interaction with the medium generates a trail of condensation droplets or bubbles in a liquid. The application of an external electric or magnetic field provides the means of “steering” the particle in motion (acting as a current) under the influence of Lorentz force. The first cloud chamber was constructed in 1912 by Charles Thomson Rees Wilson (1869–1959) from Scotland, UK, for which he received the Nobel Prize in Physics in 1927 (shared with Arthur Holly Compton [1892–1962]). The bubble chamber evolved later as introduced by Donald Arthur Glaser (1926–2013) from the United States in 1952 (for which he received the Nobel Prize in Physics in 1960) (see Figure B.67).
Visualization and numerical investigations on heterogeneous nucleation of water vapor on the surface of SiO2, Fe2O3 and CaSO4 particles
Published in Aerosol Science and Technology, 2022
Li Lv, Anwen Dai, Xiaohui Ye, Jie Yin, Junchao Xu, Jun Zhang
Importantly, in this work of heterogeneous nucleation on Fe2O3, SiO2 and CaSO4 particles, it can be found that the theoretical prediction results basically match with the experimental results. Apart from the experimental Scr of CaSO4 particles is very close to theoretical results, the experimental Scr on the surface of SiO2 and Fe2O3 particles are lower than the theoretical value. For example, for SiO2 and Fe2O3 particles with a diameter of 1.0 µm, the theoretical Scr predicted based on the classical nucleation theory are 1.0433 and 1.1388, respectively, while the experimental Scr are 1.0332 and 1.1283, respectively. This phenomenon is not only consistent with our previous comparison between experimental critical supersaturation and theoretical results on SiO2 particles with size range of 1.0–10.0 µm (Lv, Zhang, and Xu 2020a), but also consistent with Chen's results (1998). Chen investigated heterogeneous nucleation of water vapor on sub-micrometer particles in a flow cloud chamber and determined the size dependence of experimental critical supersaturation on SiC, SiO2 and naphthalene particles. The results showed that the experimental critical supersaturation is smaller than that predicted by the Fletcher’s theory of heterogeneous nucleation even considering the effects of the line tension and surface diffusion. So it was concluded that the macroscopic theory of heterogeneous nucleation underestimated the nucleation rate and predicted a higher critical supersaturation than that experimentally measured. In this work, water depletion is not considered in the ESEM chamber since a continuous supply of supersaturated water vapor required for nucleation is created sufficiently by water evaporation from a built-in water reservoir. Thus the nucleation ability of Fe2O3, SiO2 and CaSO4 particles in the experiment is much stronger than theoretical predictions.