Tim Mortensen

Tim Mortensen
Swansea University | SWAN · Welsh Centre for Printing and Coating "WCPC"

MPhys

About

12
Publications
4,728
Reads
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235
Citations
Citations since 2017
2 Research Items
181 Citations
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Introduction
Additional affiliations
July 2014 - present
Swansea University
Position
  • Researcher
Description
  • Working with printed electronics in a range of areas including pressure sensors and wireless power.
July 2013 - July 2014
Université Paris-Saclay
Position
  • Researcher
Description
  • Developing a Linac based positron accumulator with the aim of holding record numbers of positrons for an antihydrogen experiment to determine the effect of gravity on antimatter.
Education
September 2009 - June 2013
Swansea University
Field of study
  • Physics

Publications

Publications (12)
Article
This article details the development of a thin film piezoresistive screen printed pressure sensor on a flexible substrate using a composite ink based on functionalised graphene nanoplatelets (GNPs). The sensor operates through direct interfacial contact between two distinct films of the composite ink deposited over conductive substrates, without re...
Article
Full-text available
A tunable, pulsed laser was used to excite the Lyman-α transition (1S-2P) of positronium (Ps). The laser system has a large bandwidth of GHz at nm, providing significant coverage of the Doppler-broadened, single-photon transition. The infra-red fundamental of a Nd:YAG laser was converted to ultraviolet by a series of solid-state, nonlinear processe...
Article
Full-text available
The GBAR project (Gravitational Behaviour of Anti hydrogen at Rest) at CERN, aims to measure the free fall acceleration of ultracold neutral anti hydrogen atoms in the terrestrial gravitational field. The experiment consists preparing anti hydrogen ions (one antiproton and two positrons) and sympathetically cooling them with Be + ions to less than...
Article
Full-text available
The specific antiproton- and positron-beam requirements of the CERN AD-7 experiment, GBAR (Gravitational Behavior of Antimatter at Rest) are presented. GBAR will synthesize antihydrogen ions which will be sympathetically cooled before performing a free-fall experiment on the atom. Antiprotons delivered by CERN's ELENA facility in 100-keV, 300-ns pu...
Article
Full-text available
The anharmonic component of the electric field of a Penning–Malmberg trap is exploited to manipulate a subset of the radial (r) distribution of trapped positrons, using a dipole field made to rotate about the long-axis (z) of the trap. This 'rotating wall' technique (RW) induces inward transport at frequencies associated with the motion of trapped...
Article
Full-text available
We describe a simple and versatile method to manipulate the amplitude of the magnetron orbit of ions stored in a Penning trap, applied here to a cloud of low energy positrons. By applying a pulsed voltage to a split electrode in the trap, which is normally used for rotating wall compression of the particles, the size of the magnetron orbit can be c...
Article
Full-text available
Positron clouds are compressed following accumulation in a Surko-type two-stage buffer gas trap using an asymmetric rotating wall electric field. An analytic theory used to describe measurements of the rate of compression is discussed. Furthermore, we describe measurements taken without the rotating wall applied and with the rotating wall compressi...
Article
An asymmetric dipolar rotating electric field can be used to compress a trapped cloud of positrons when applied with a frequency close that of their axial bounce, and in the presence of a low pressure molecular gas to provide cooling. Measurements of the compression rate and associated parameters are presented and compared with results of a theory...
Article
The application of an asymmetric dipolar electric field rotating at a frequency close to that of the axial bounce of a collection of trapped positrons has, in the presence of a low pressure molecular gas to provide cooling, been used to achieve compression of the cloud. A theory of this effect has been developed for a Penning trap potential, with t...

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