Magnetic quenching of positronium studied by positron annihilation lifetime and Doppler broadening measurements

2020 ◽  
Vol 171 ◽  
pp. 108712
Author(s):  
J.D. Liu ◽  
J.Q. Guo ◽  
M. Luo ◽  
Z. Wang ◽  
H.J. Zhang ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Doppler Broadening ◽  
Positron Annihilation Lifetime

Annihilation Lifetime Spectroscopy Using Positrons from Bremsstrahlung Production

2012 ◽  
Vol 331 ◽  
pp. 41-52 ◽  
Author(s):  
Andreas Wagner ◽  
Wolfgang Anwand ◽  
Maik Butterling ◽  
Thomas E. Cowan ◽  
Fine Fiedler ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Linear Accelerator ◽  
Electron Accelerator ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Electron Linear Accelerator ◽  
Positron Annihilation Lifetime ◽  
Electron Bremsstrahlung ◽  
New Type ◽  
Set Up

A new type of a positron annihilation lifetime spectroscopy (PALS) system has been set up at the superconducting electron accelerator ELBE [ at Helmholtz-Zentrum Dresden-Rossendorf. In contrast to existing source-based PALS systems, the approach described here makes use of an intense photon beam from electron bremsstrahlung which converts through pair production into positrons inside the sample under study. The article focusses on the production of intense bremsstrahlung using a superconducting electron linear accelerator, the production of positrons inside the sample under study, the efficient detector setup which allows for annihilation lifetime and Doppler-broadening spectroscopy simultaneously. Selected examples of positron annihilation spectroscopy are presented.

Positron annihilation lifetime and coincidence Doppler broadening study of γ-irradiated polyethylene

2005 ◽  
Vol 313 (1-3) ◽  
pp. 63-69 ◽  
Author(s):  
R.S. Yu ◽  
T. Suzuki ◽  
N. Djourelov ◽  
K. Kondo ◽  
Yasuo Ito ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Doppler Broadening ◽  
Positron Annihilation Lifetime ◽  
Coincidence Doppler Broadening

Positron Annihilation in IR Transmitting GeS2-Ga2S3 Glasses

2015 ◽  
Vol 230 ◽  
pp. 221-227 ◽  
Author(s):  
Halyna Klym ◽  
A. Ingram ◽  
O. Shpotyuk ◽  
R. Szatanik ◽  
E. Petracovschi ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Decisive Role ◽  
Density Variation ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Annihilation Radiation ◽  
Doppler Broadening ◽  
Positron Annihilation Lifetime ◽  
Positron Trapping ◽  
Trapping Process

Positron annihilation lifetime spectroscopy combined with Doppler broadening of annihilation radiation was applied to study free-volume entities in GeS2-Ga2S3glasses affected by Ga additions. It is shown that Ga-related void sub-system plays a decisive role in positron trapping process, while the overall density variation is defined mainly by Ge-related sub-system. These results serve as basis for new characterization route for inner free-volume structure of these glasses.

POSITRON INTERACTION IN POLYMERS

2004 ◽  
Vol 19 (23) ◽  
pp. 3951-3959 ◽  
Author(s):  
CORINE BAS ◽  
N. DOMINIQUE ALBÉROLA ◽  
MARIE-FRANCE BARTHE ◽  
JÉRÉMIE De BAERDEMAEKER ◽  
CHARLES DAUWE
Keyword(s):  
Positron Annihilation ◽  
Chemical Structure ◽  
Positron Beam ◽  
Positron Annihilation Spectroscopy ◽  
Hole Size ◽  
Doppler Broadening ◽  
Positron Source ◽  
Positron Annihilation Lifetime ◽  
Doppler Broadening Spectra ◽  
Variable Energy

A series of dense copolyimide membranes was characterized using positron annihilation spectroscopy. The positron annihilation lifetime spectroscopy performed on film with a classical positron source gives informations on the positronium fraction formed and also on the hole size within the film. The Doppler broadening spectra (DBS) of the gamma annihilation rays coupled with a variable energy positron beam allow the microstructural analyses as a function of the film depth. Experimental data were also linked to the chemical structure of the polyimides. It was found that the presence of the fluorine atoms strongly affects the positron annihilitation process and especially the DBS responses.

scholarly journals On the consistency between positron annihilation lifetime and Doppler broadening results in polypropylene

2007 ◽  
Vol 4 (10) ◽  
pp. 3710-3713 ◽  
Author(s):  
N. Djourelov ◽  
C. Dauwe ◽  
C. A. Palacio ◽  
N. Laforest ◽  
C. Bas
Keyword(s):  
Positron Annihilation ◽  
Doppler Broadening ◽  
Positron Annihilation Lifetime

scholarly journals Study of multiblock polyamide-6/Poly-(isoprene) copolymers by positron annihilation spectroscopy

2008 ◽  
Vol 6 (4) ◽  
pp. 575-580 ◽  
Author(s):  
R. Bryaskova ◽  
R. Mateva ◽  
N. Djourelov ◽  
M. Krasteva
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Main Chain ◽  
Positron Annihilation Spectroscopy ◽  
Polyamide 6 ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Degree Of Crystallinity ◽  
Doppler Broadening ◽  
Annihilation Line ◽  
Positron Annihilation Lifetime

AbstractPositron annihilation lifetime spectroscopy (PALS) has been used to determine the free volume in multiblock polyamide-6/poly-(isoprene) copolymers (PA-6/PI), synthesized via activated anionic bulk copolymerization. The diisocyanate functionalized telechelic PI, blocked with caprolactam (CL) has been used as a commoner and an activator at the same time. The elastic PI block incorporated into the main chain of PA-6 affects the amorphous and crystal phase of the copolymer leading to changing in degree of crystallinity. The positron annihilation lifetime spectroscopy (PAL) and Doppler broadening of annihilation line (DBAL) technique in a set of pure PA-6 and PA-6/PI copolymers with two different compositions have been applied and evaluation of the size of free-volume holes (pores), localized mainly in the disordered regions of the PA-6/PI copolymer by measuring the o-Ps lifetime (τ3) and o-Ps intensity (I3) has been performed.

Temperature Dependence of Radiation Damage in ODS Steel Studied by Triple Beam Irradiation and Positron Annihilation Techniques

2017 ◽  
Vol 373 ◽  
pp. 91-95 ◽  
Author(s):  
Da Qing Yuan ◽  
Qiao Li Zhang ◽  
Ping Fan ◽  
Xian Ping Wang ◽  
Bin Long ◽  
...  
Keyword(s):  
Radiation Damage ◽  
Positron Annihilation ◽  
Ion Beam ◽  
Positron Beam ◽  
Doppler Broadening ◽  
Beam Irradiation ◽  
Single Beam ◽  
Positron Annihilation Lifetime ◽  
Ods Steel ◽  
S Parameter

The oxide dispersed strengthened (ODS) ferritic-martensitic steel was irradiated by 100MeV iron ion whose energy was degraded by using a Ta foil of 4 μm thick, 100 keV Hydrogen and 200 keV Helium at 480, 515, 550 and 580 °C. The irradiation fluences were 1×1016, 1.1×1015 and 6.8×1013/cm2, respectively for Fe, H and He. The techniques of positron annihilation lifetime and Doppler broadening of slow positron beam were utilized to examine the produced radiation damage. At 550 °C the maximal positron annihilation lifetime and S parameter of Doppler broadening were observed, implyin g tha t 550 °C is the pea k temperature of swelling. The S parameter and annihilation lifetime of the sample irradiated at 515 °C by the single Fe ion beam were smaller compared to the triple beam irradiation at the same temperature, implying that the triple beam irradiation caused more severe damage than the single beam irradiation.

Study of Defects Introduced by 2 and 9 MeV Electron Irradiation in B2 Type Fe-Al Alloy

2017 ◽  
Vol 373 ◽  
pp. 126-129
Author(s):  
Youhei Ueno ◽  
Akihiro Iwase ◽  
Kazuhito Ohsawa ◽  
Qiu Xu ◽  
Koichi Sato ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Electron Irradiation ◽  
Threshold Energy ◽  
Al Alloy ◽  
Doppler Broadening ◽  
Intermetallic Alloys ◽  
Positron Annihilation Lifetime ◽  
Different Types ◽  
Show Difference ◽  
Compound Alloy

It is well known that intermetallic compound alloys possibly include more than two types of vacancies basically, that is A-vacancy and B-vacancy in A-B compound alloy. Although MeV ordered electron irradiation produces vacancies and interstitials, the threshold energy of displacement for each elemental atom in intermetallic alloys is not necessarily same. Then the defect type introduced by the irradiation depends on electron energy. In this study, we performed positron annihilation lifetime and Doppler broadening measurements for different energy of electron irradiated B2 type Fe50%Al alloy. The values of positron annihilation lifetime for this alloy after 2 and 9 MeV electron irradiation were 200 and 172 psec, respectively. Also, the Doppler broadening parameters S and W show difference for this alloy with different energy of electron irradiation. These results suggest that different types of vacancy were induced into Fe-Al compound alloy by electron irradiation with different energies.

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