Measurement of the Loss and Depolarization Probability of UCN on Beryllium and Diamond Like Carbon Films.
Currently several institutes worldwide are working on the development of a new generation of ultracold neutron (UCN) sources. In parallel with source development, new materials for guiding and storage of UCN are developed. Currently the best results have been achieved using (58)Ni, Be, solid O2 and low temperature Fomblin oil (LTF). All of these materials have their shortcomings like cost, toxicity or difficulty of use. A novel very promising material is diamond like carbon (DLC). Several techniques exist to coat surfaces, and industrial applications (e.g., for extremely hard surfaces) are already wide spread. Preliminary investigations using neutron reflectometry at PSI and Los Alamos yielded a critical velocity for DLC of about 7 m/s thus comparable to Beryllium. A low upper limit of depolarization probability for stored polarized UCN has been measured at the PF2 facility of the Institut Laue-Langevin (ILL) by North Carolina State University (NCSU), Los Alamos National Laboratory (LANL), and Petersburg Nuclear Physics Institute (PNPI), thus making it also a good material for storage and guidance of polarized UCN. Still missing is the loss probability per bounce. We will be able to extract this number and a more stringent value for the depolarization from our experiment thus proving the suitability of DLC as a wall material for a wide range of UCN applications.
Paul Scherrer Institut, 5232 Villingen PSI, Switzerland and ETH Zürich, Zurich, Switzerland.
Tomas
T
Brys
Paul Scherrer Institut, 5232 Villingen PSI, Switzerland.
Manfred
M
Daum
Paul Scherrer Institut, 5232 Villingen PSI, Switzerland and Universitaet Zürich, Zurich, Switzerland.
Peter
P
Fierlinger
Institut Laue Lagevin, Grenoble, France.
Peter
P
Geltenbort
Paul Scherrer Institut, 5232 Villingen PSI, Switzerland.
Mukul
M
Gupta
Paul Scherrer Institut, 5232 Villingen PSI, Switzerland.
Reinhold
R
Henneck
Paul Scherrer Institut, 5232 Villingen PSI, Switzerland and Universitaet Zürich, Zurich, Switzerland.
Stefan
S
Heule
Paul Scherrer Institut, 5232 Villingen PSI, Switzerland.
Klaus
K
Kirch
PNPI Gatchina, Russia.
Mikhail
M
Lasakov
Virginia Tech, Blacksburg, USA.
Russel
R
Mammei
Virginia Tech, Blacksburg, USA.
Mark
M
Makela
Paul Scherrer Institut, 5232 Villingen PSI, Switzerland.
Axel
A
Pichlmaier
Paul Scherrer Institut, 5232 Villingen PSI, Switzerland and PNPI Gatchina, Russia.
Anatoli
A
Serebrov
Universitaet Zürich, Zurich, Switzerland.
Ulrich
U
Straumann
Virginia Tech, Blacksburg, USA.
Robert B
RB
Vogelaar
ETH Zürich, Zurich, Switzerland and Paul Scherrer Institut, 5232 Villingen PSI, Switzerland.
Cedric
C
Wermelinger
North Carolina State University, Raleigh, USA.
Albert
A
Young
depolarization; diamond like carbon; spin flip; ultracold neutrons