75 research outputs found
Mapping the Sensitive Volume of an Ion-Counting Nanodosimeter
We present two methods of independently mapping the dimensions of the
sensitive volume in an ion-counting nanodosimeter. The first method is based on
a calculational approach simulating the extraction of ions from the sensitive
volume, and the second method on probing the sensitive volume with 250 MeV
protons. Sensitive-volume maps obtained with both methods are compared and
systematic errors inherent in both methods are quantified.Comment: 27 pages, 8 figures. Submitted to JINST, Jan. 16 200
On deep speaker embeddings for text-independent speaker recognition
We investigate deep neural network performance in the textindependent speaker
recognition task. We demonstrate that using angular softmax activation at the
last classification layer of a classification neural network instead of a
simple softmax activation allows to train a more generalized discriminative
speaker embedding extractor. Cosine similarity is an effective metric for
speaker verification in this embedding space. We also address the problem of
choosing an architecture for the extractor. We found that deep networks with
residual frame level connections outperform wide but relatively shallow
architectures. This paper also proposes several improvements for previous
DNN-based extractor systems to increase the speaker recognition accuracy. We
show that the discriminatively trained similarity metric learning approach
outperforms the standard LDA-PLDA method as an embedding backend. The results
obtained on Speakers in the Wild and NIST SRE 2016 evaluation sets demonstrate
robustness of the proposed systems when dealing with close to real-life
conditions.Comment: Submitted to Odyssey 201
Progress with Xenon Liquid Hole Multipliers
The bubble-assisted Liquid Hole Multiplier (LHM) is a recently-proposed
concept for the combined detection of ionization electrons and primary
scintillation photons in noble-liquid time projection chambers. The LHM
comprises a perforated micro-pattern electrode (e.g. Thick Gas Electron
Multiplier - THGEM, or Gas Electron Multiplier - GEM) immersed in the liquid,
with a bubble of the noble gas supported underneath. Ionization electrons and
scintillation-induced photoelectrons extracted from a cesium iodide
photocathode drift through the electrode's holes and induce electroluminescence
(EL) signals in the bubble; these are recorded by photon detectors located
closely below the electrode. We present recent results in the development of
LHMs, comparing the response of different electrodes to ionization and
photon-induced electrons.Comment: Presented at 2016 IEEE NSS/MIC, Strasbourg, France, 29 October - 5
November 201
- …