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Super K

Super-Kamiokande (abbreviation of Super-Kamioka Neutrino Detection Experiment, also abbreviated to Super-K or SK; Japanese: スーパーカミオカンデ) is a neutrino observatory located under Mount Ikeno near the city of Hida, Gifu Prefecture, Japan. It is located 1,000 m (3,300 ft) underground in the Mozumi Mine in Hida's Kamioka area. The observatory was designed to detect high-energy neutrinos, to search for proton decay, study solar and atmospheric neutrinos, and keep watch for supernovae in the Milky Way Galaxy.

Super K

The Super-K is located 1,000 m (3,300 ft) underground in the Mozumi Mine in Hida's Kamioka area.[2][3] It consists of a cylindrical stainless steel tank that is 41.4 m (136 ft) tall and 39.3 m (129 ft) in diameter holding 50,220 metric tons (55,360 US tons) of ultrapure water. The tank volume is divided by a stainless steel superstructure into an inner detector (ID) region, which is 36.2 m (119 ft) in height and 33.8 m (111 ft) in diameter, and outer detector (OD) which consists of the remaining tank volume. Mounted on the superstructure are 11,146 photomultiplier tubes (PMT) 50 cm (20 in) in diameter that face the ID and 1,885 20 cm (8 in) PMTs that face the OD. There is a Tyvek and blacksheet barrier attached to the superstructure that optically separates the ID and OD.[citation needed]

The detector, named KamiokaNDE for Kamioka Nucleon Decay Experiment, was a tank 16.0 m (52 ft) in height and 15.6 m (51.2 ft) in width, containing 3,058 metric tons (3,400 US tons) of pure water and about 1,000 photomultiplier tubes (PMTs) attached to its inner surface. The detector was upgraded, starting in 1985, to allow it to observe solar neutrinos. As a result, the detector (KamiokaNDE-II) had become sensitive enough to detect neutrinos from SN 1987A, a supernova which was observed in the Large Magellanic Cloud in February 1987, and to observe solar neutrinos in 1988. The ability of the Kamiokande experiment to observe the direction of electrons produced in solar neutrino interactions allowed experimenters to directly demonstrate for the first time that the Sun was a source of neutrinos.

The Super-Kamiokande (SK) is a Cherenkov detector used to study neutrinos from different sources including the Sun, supernovae, the atmosphere, and accelerators. It is also used to search for proton decay. The experiment began in April 1996 and was shut down for maintenance in July 2001, a period known as "SK-I". Since an accident occurred during maintenance, the experiment resumed in October 2002 with only half of its original number of ID-PMTs. In order to prevent further accidents, all of the ID-PMTs were covered by fiber-reinforced plastic with acrylic front windows. This phase from October 2002 to another closure for an entire reconstruction in October 2005 is called "SK-II". In July 2006, the experiment resumed with the full number of PMTs and stopped in September 2008 for electronics upgrades. This period was known as "SK-III". The period after 2008 is known as "SK-IV". The phases and their main characteristics are summarised in table 1.[14]

Nuclear fusion in the Sun and other stars turns protons into neutrons with the emission of neutrinos. Beta decay in the Earth and in supernovas turns neutrons into protons with the emission of anti-neutrinos. The Super-Kamiokande detects electrons knocked off a water molecule producing a flash of blue Cherenkov light, and these are produced both by neutrinos and antineutrinos. A rarer instance is when an antineutrino interacts with a proton in water to produce a neutron and a positron.[19]

Gadolinium has an affinity for neutrons and produces a bright flash of gamma rays when it absorbs one. Adding gadolinium to the Super-Kamiokande allows it to distinguish between neutrinos and antineutrinos. Antineutrinos produce a double flash of light about 30 microseconds apart, first when the neutrino hits a proton and second when gadolinium absorbs a neutron.[17] The brightness of the first flash allows physicists to distinguish between low energy antineutrinos from the Earth and high energy antineutrinos from supernovas. In addition to observing neutrinos from distant supernovas, the Super-Kamiokande will be able to set off an alarm to inform astronomers around the world of the presence of a supernova in the Milky Way within one second of it occurring.

The basic unit for the ID PMTs is a "supermodule", a frame which supports a 34 array of PMTs. Supermodule frames are 2.1 m in height, 2.8 m in width and 0.55 m in thickness. These frames are connected to each other in both the vertical and horizontal directions. Then the whole support structure is connected to the bottom of the tank and to the top structure. In addition to serving as rigid structural elements, supermodules simplified the initial assembly of the ID. Each supermodule was assembled on the tank floor and then hoisted into its final position. Thus the ID is in effect tiled with supermodules. During installation, ID PMTs were pre-assembled in units of three for easy installation. Each supermodule has two OD PMTs attached on its back side. The support structure for the bottom PMTs is attached to the bottom of the stainless-steel tank by one vertical beam per supermodule frame. The support structure for the top of the tank is also used as the support structure for the top PMTs.

To detect and identify such bursts as efficiently and promptly as possible Super-Kamiokande is equipped with an online supernova monitor system. About 10,000 total events are expected in Super-Kamiokande for a supernova explosion at the center of the Milky Way Galaxy. Super-Kamiokande can measure a burst with no dead-time, up to 30,000 events within the first second of a burst. Theoretical calculations of supernova explosions suggest that neutrinos are emitted over a total time-scale of tens of seconds with about a half of them emitted during the first one or two seconds. The Super-K will search for event clusters in specified time windows of 0.5, 2 and 10 s.[9] Data are transmitted to realtime SN-watch analysis process every 2 min and analysis is completed typically in 1 min. When supernova (SN) event candidates are found, R mean \displaystyle R_\textmean is calculated if the event multiplicity is larger than 16, where R mean \displaystyle R_\textmean is defined as the average spatial distance between events, i.e.

Offering a glimpse into the world of particle physics, NBH Studios created a super-sized version of a Japanese neutrino observatory, where electrons and neutrinos, a type of fundamental particles that make up the universe, collide to create giant explosions. On entering the installation, visitors put on helmets, white rubber shoes and boiler suits. They then board dinghies that transport them through a space filled with water and covered with silver balloons where they meet the Nobel Prize Physics winner inside a boat. There, they experienced a light show and a sonic explosion designed by sound artist Tim Holden in partnership with Particle Physicist at Imperial College.

The Aogami Super line is arguably one of the most underrated offering from Sukenari. The reason? While staying at a very affordable price, the Sukenari Aogami Super is forged and water quenched to an extremely high hardness of HRC 65 (previously, the damascus version was even higher, more than HRC 66). This means a super high hardness, extreme sharpness and edge retention, but it also comes with an extremely high failure rate.

Koshiba and his colleagues conceived to build a detector of about 2000 tons of water (inner volume) surrounded by \(\sim 1000\) PMTs (photo-multiplier tubes) of 50 cm in diameter to look for proton decay [1] to test grand unified theories. In 1982, the project called KamiokaNDE (Kamioka Nucleon Decay Experiment) was funded. Although the primary aim was to conduct an extensive search for proton decay, possibilities to make a study on neutrino oscillations through atmospheric neutrinos and to detect neutrino bursts from supernovae were mentioned in their proposal, however a possible observation of solar neutrinos was not explicitly referred [2].

Responding to the proposed detector improvement, a US group (mostly from University of Pennsylvania) joined and the new Collaboration, Kamiokande-II, was formed. New TDC modules were arranged by the US group. An anti-counter was newly installed and a water circulation system was introduced. After fighting against the low energy backgrounds mostly from the Rn contamination in water, the experiment had succeeded to lower the energy threshold. Kamiokande-II started in early 1987, and immediately after that the historical observation of the neutrino burst from supernova SN1987A [8] was made, which demonstrated the excellent capability of water Cherenkov detectors to measure low energy neutrinos. A couple of years later Kamiokande-II also had succeeded to detect solar neutrinos and confirmed the deficit of neutrinos from the sun [9].

Super-K was funded in 1991 and its construction took 5 years. It was just 4 years after the historical observation of the neutrino burst from the supernova in our adjacent galaxy. In 1992, 1 year after the start of the construction of the detector, a US group who had been working on the IMB experiment had joined the Super-K project. They took the responsibility to fabricate an outer detector system including photo-sensors. The excavation of the cavity for the detector finished in June 1994. The stainless steal water tank had been constructed from June 1994 to June 1995. It took about 6 months to install the photomultiplier tubes (PMTs), electronics and data acquisition system. We had started to fill the detector with water in January, 1996. Figure 2. shows the moment when Yoji Totsuka pressed the button to start the experiment punctually at 0:00 on April 1st, 1996.

With this new electronics system, Super-K acquires a few new features. The individual neutrino events in a neutrino burst from supernovae can detect up to 6 million events for the first 10 s without any loss that is 100 times better than the previous Super-K phases. The detection efficiency for the \(\mu \rightarrow e\) decays reaches about 100% for the first \(1\mu \hbox s\). The detection of \(2.2\hbox MeV \gamma \) after neutron capture becomes possible. These capabilities were impossible in the previous system. 041b061a72


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