Neutron Lifetime Experiment Based on an Accordion-Like UCN Storage Volume Coated With "Low Temperature Fomblin"

B Yerozolimsky; A Steyerl; O Kwon; V Luschikov; A Strelkov; P Geltenbort; N Achiwa; A Pichlmaier; P Fierlinger

doi:10.6028/jres.110.052

Neutron Lifetime Experiment Based on an Accordion-Like UCN Storage Volume Coated With "Low Temperature Fomblin"

J Res Natl Inst Stand Technol. 2005 Aug 1;110(4):351-6. doi: 10.6028/jres.110.052. Print 2005 Jul-Aug.

Authors

B Yerozolimsky¹, A Steyerl², O Kwon², V Luschikov³, A Strelkov³, P Geltenbort⁴, N Achiwa⁵, A Pichlmaier⁶, P Fierlinger⁶

Affiliations

¹ Harvard University, Cambridge, MA, USA.
² University of Rhode Island, Kingston, RI, USA.
³ Joint Institute for Nuclear Research, Dubna, Russia.
⁴ Institut Laue Langevin, Grenoble, France.
⁵ Osaka University, Japan.
⁶ Paul Scherrer Institut, Villigen, Switzerland.

Abstract

A new type of per-fluorinated polymer, "Low Temperature Fomblin," has been tested as a wall coating in an ultracold neutron (UCN) storage experiment using a gravitational storage system. The data show a UCN reflection loss coefficient η as low as ≈ 5 × 10(-6) in the temperature range 105 K to 150 K. We plan to use this oil in a new type of neutron lifetime measurement, where a bellows system ("accordion") enables to vary the trap size in a wide range while the total surface area and distribution of surface area over height remain constant. These unique characteristics, in combination with application of the scaling technique developed by W. Mampe et al. in 1989, ensure exact linearity for the extrapolation from inverse storage lifetimes to the inverse neutron lifetime. Linearity holds for any energy dependence of loss coefficient µ(E). Using the UCN source at the Institut Laue Langevin we expect to achieve a lifetime precision below ±1 s.

Keywords: neutron lifetime; ultracold neutrons.