Xinhua News Agency, Chengdu, January 27th: A “panda†is growing vigorously in the underground laboratory of China Jinping at 2,500 meters underground in the Jinping hydropower station on the Yalong River in Sichuan. It won't be a treasure, but it is peeping into the universe "ghost" - dark matter.
This "panda" named PandaX is an English shorthand for the "particle and astrophysics æ°™ detector." This experiment uses the inert element helium purified in the air as a detection medium to search for dark matter, led by Shanghai Jiaotong University.
The reporter recently learned from the experimental group that the current size of liquid helium in the core area of ​​the detector is being upgraded from the first stage of 120 kg to the second stage of 500 kg. After the completion of the upgrade in 2015, it is expected to become the most sensitive dark matter detector in the world.
Professor Shi Xiangdong, a professor at Shanghai Jiaotong University and an expert on the National Thousand Talents Program, likens dark matter to the “ghost†in the universe. He said that research and analysis so far have shown that the share of dark matter in the universe far exceeds what humans can currently see, and the common material we usually observe only accounts for 5% of the mass of the universe. Dark matter does not interact with ordinary substances, so detection is difficult. Dark matter and dark energy are referred to as "two dark clouds" in the modern sky in the 21st century modern physics and astronomy.
It is understood that PandaX uses liquid helium technology to cool helium to minus 100 degrees Celsius. When dark matter collides with helium atoms, helium atoms will emit light, and free electrons will also be generated. The scientist's job is to find ways to detect these faint light and several free electrons, and at the same time confirm that these signals are not caused by other reasons.
According to Liu Jiang, a researcher specializing in physics and astronomy at the Shanghai Jiaotong University, if dark matter is the "fog and haze" in the universe, the earth is a car that runs in fog, and when the particles in the fog hit the car, it will make a "sound". The task of the detection instrument is to record this "sound".
Since the beginning of this century, more than 20 dark matter detection experiments have been carried out in the world. The Italian DAMA/LIBRA experiment, the American CoGeNT and CDMS experiments, and the German CRESST experiment have allegedly discovered a signal suspected of a light-weight dark matter. The main difficulty in such experiments is the cosmic rays and the ubiquitous radioactivity on Earth. For PandaX, the 2500-meter-thick rock layer above it reduces the cosmic flux to very low levels. At the same time, the rock is mainly marble. There is no much radiation material, and it is far away from radiation sources that cause false signals.
In August 2014, the PandaX experimental group published the first batch of data obtained during the first phase of the experiment, questioning the previously internationally suspected suspected dark matter signal.
At our factory outlet, we offer a wide range of hot-selling graphite moulds for casting. These moulds are manufactured using high-quality graphite materials, ensuring durability and long-lasting performance. Our graphite moulds are designed to withstand high temperatures and provide excellent dimensional accuracy for producing high-quality castings.
Some of our popular graphite moulds for casting include:
1. Graphite Ingot Moulds: These moulds are used for casting metal ingots, such as gold, silver, and other precious metals. They come in various sizes and shapes to accommodate different casting requirements.
2. Graphite Crucibles: Crucibles are essential for melting and pouring molten metal into moulds. Our graphite crucibles are highly resistant to thermal shock and have excellent heat retention properties.
3. Graphite Dies: Dies are used for casting complex shapes and intricate parts. Our graphite dies are precision-machined to ensure accurate and repeatable casting results.
4. Graphite Plates: Plates are used for casting flat or thin metal parts. Our graphite plates are available in various thicknesses and sizes to meet different casting needs.
5. Graphite Rings: Rings are commonly used for casting cylindrical or round-shaped metal parts. Our graphite rings are highly durable and can withstand high temperatures and pressures.
All our graphite moulds are carefully crafted to meet the highest quality standards. They undergo rigorous quality checks to ensure they are free from defects and can provide consistent and reliable casting results.
If you are looking for high-quality graphite moulds for casting, visit our factory outlet to explore our wide range of hot-selling products. Our knowledgeable staff will assist you in finding the right moulds for your specific casting requirements.
Graphite Mould,Graphite Bar,Graphite Plate Sheets,Graphite Ingot Mould
Yixing Xingfeng Carbide Mould Co.,LTD , https://www.xfcarbidemould.com