NEDM Essay Example | Topics and Well Written Essays - 5000 words

NEDM - Essay Example The room – temperature experiment was carried out in Institut Laue-Langevin (ILL) and the final results from this research were published in 2006.3 4 A thorough discussion of the experiment’s apparatus and flow process are included in this review. Ultra-cold neutrons are utilized in the room-temperature experiment; these are generated by the UCN turbine. To begin the process, UCNs ‘entered the apparatus from the lower right (as indicated by the red arrow in Figure 1) and flowed upwards to the polarizer foil’.8 Harris described the UCNs behaviour as similar to ‘a diffuse gas’.9 He further explained, Those of the correct spin passed through the foil and continued to rise until they reached the storage bottle at the heart of the apparatus. The bottle was located in a 10 mG (1 ÃŽ ¼T) vertical magnetic field; four layers of mu-metal were used to shield out external fields, including that of the Earth. After a filling period of about 20 seconds, the neutron door was closed, and the Ramsey sequence was applied to the trapped neutrons. The door was then opened, and the neutrons fell back down to the polarizer, which then acted as an analyser. Those in the original spin state could pass through and down to a gaseous 3He neutron detector (the curved guide tube from the source having been moved aside in favour of a vertical guide leading to the detector). Neutrons of the â€Å"wrong† spin state, which bounced off the polarizer, were counted in their turn by employing a fast-passage adiabatic spin flipper to reverse the direction of the spins of the neutrons in the guide tube just above the polarizer: this spin flipper consisted simply of a solenoid wrapped around the guide tube, situated in a region of magnetic field gradient, to which a high-frequency (20 kHz) alternating current was applied.10 The time needed to process each batch of neutrons takes about