(image: the portal where ultracold neutrons (UCNs) exit and are collected and counted. The UCNs' extremely low velocities and energy make them ideal for investigating fundamental physics properties)
The Ultracold Neutron Facility at TRIUMF
On Monday, November 13th, 2017, the TUCAN Collaboration at TRIUMF achieved a major milestone by producing the first ultracold neutrons (UCNs) ever created in Canada.
The Japanese-Canadian TUCAN (TRIUMF Ultra Cold Advanced Neutron source) collaboration formed in 2010 with the goal of creating the world's most intense UCN source to measure the nEDM with unprecedented precision. Between 2014 and 2016, a new proton beamline at TRIUMF was constructed to supply a spallation target for neutron production. During the most recent TRIUMF's annual cyclotron shutdown period, the UCN source prototype from Japan was installed above the target. The secret behind creating UCNs lies in superfluid helium, which is cooled down to a temperature of less than 1 degree above absolute zero (<1K).
The TUCAN collaboration celebrated its first major milestone in November 2016 when it achieved its first beam-on-target; just a year later, the newly-installed UCN cryostat reached its design temperature of approximately 0.8K. Now, the first Canadian UCNs have been created from hot spallation neutrons produced using a 1 microamp, 480 MeV proton beam. The approximate 50000 UCNs counted per “shot” (pulse of protons on target) were well within expectation, enabling the planned experimental program to be carried out. This will include characterizing the source to aid in the development of the next-generation source, with which TUCAN hopes to achieve orders of magnitude more UCNs. The upgraded source will be deployed for the flagship nEDM experiment, which TUCAN hopes to run by 2020.(image: members of the TRIUMF UCN team celebrating UCN production success)
(image: Graph showing the number of ultracold neutrons (UCNs) detected as a function of time for one production cycle. Each cycle consists of irradiating the neutron-production target with a 1 microamp, 480 MeV proton beam for 60 seconds. The decay curve indicates the diminishing number of UCNs in the detection chamber as a result of various loss mechanisms, e.g. absorption in the walls, neutron decay, etc. The number of initial UCNs produced and the loss curve are well within expectations)
Congratulations to the TUCAN and UCN facility teams!
This project is led by the University of Winnipeg under principal investigator Prof. Jeff Martin and is supported by TRIUMF, CFI, BCKDF, MRF, and NSERC in Canada, and by KEK and RCNP in Japan.