PRESENT STATUS OF ALPHA-PARTICLE CONDENSATE STATES IN SELF-CONJUGATE 4n NUCLEI

2008 ◽  
Vol 17 (10) ◽  
pp. 2087-2095 ◽  
Author(s):  
Y. FUNAKI ◽  
T. YAMADA ◽  
H. HORIUCHI ◽  
G. RÖPKE ◽  
P. SCHUCK ◽  
...  
Keyword(s):  
Alpha Particle ◽  
Present Status ◽  
The State ◽  
Orthogonality Condition ◽  
Low Density ◽  
Breakup Threshold ◽  
Large Component ◽  
Condition Model ◽  
Strong Enhancement ◽  
Α Particles

Low density states near the 3α and 4α breakup threshold in 12 C and 16 O , respectively, are discussed in terms of the α-particle condensation. Calculations are performed in OCM (Orthogonality Condition Model) and THSR (Tohsaki-Horiuchi-Schuck-Röpke) approaches. The [Formula: see text] state in 12 C and the [Formula: see text] state in 16 C are shown to have dilute density structures and give strong enhancement of the occupation of the S-state c.o.m. orbital of the α-particles. The [Formula: see text] state in 16 C has a large component of [Formula: see text] configuration, which is another reliable evidence of the state to be of 4α condensate nature. The possibility of the existence of α-particle condensed states in heavier nα nuclei is also discussed.

ALPHA CLUSTERING AND CONDENSATION IN NUCLEI

2011 ◽  
Vol 20 (04) ◽  
pp. 874-879 ◽  
Author(s):  
Y. FUNAKI ◽  
T. YAMADA ◽  
H. HORIUCHI ◽  
G. RÖPKE ◽  
P. SCHUCK ◽  
...  
Keyword(s):  
Orthogonality Condition ◽  
Low Density ◽  
Breakup Threshold ◽  
Condition Model ◽  
Strong Enhancement ◽  
Alpha Clustering ◽  
Α Particles

Low density states near the 3α and 4α breakup threshold in 12 C and 16 O , respectively, are discussed in terms of the α-particle condensation. Calculations are performed in OCM (Orthogonality Condition Model) and THSR (Tohsaki-Horiuchi-Schuck-Röpke) approaches. The [Formula: see text] state in 12 C and the [Formula: see text] state in 16 O are shown to have dilute density structures and give strong enhancement of the occupation of the S-state c.o.m. orbital of the α-particles. The possibility of the existence of α-particle condensed states in heavier nα nuclei is also discussed.

α-PARTICLE CONDENSED STATE IN 16O

2009 ◽  
Vol 18 (10) ◽  
pp. 2083-2087
Author(s):  
Y. FUNAKI ◽  
T. YAMADA ◽  
H. HORIUCHI ◽  
G. RÖPKE ◽  
P. SCHUCK ◽  
...  
Keyword(s):  
Excited State ◽  
Strong Evidence ◽  
The State ◽  
Orthogonality Condition ◽  
Condensed State ◽  
Density Structure ◽  
Large Component ◽  
Condition Model ◽  
Strong Enhancement ◽  
Α Particles

The α-particle condensed state in 16 O is investigated by the use of 4α OCM (Orthogonality Condition Model). Low-lying spectrum in experiment is well reproduced up to around the 4α threshold. Furthermore, the excited state obtained around the 4α threshold as the [Formula: see text] state is shown to have a dilute density structure and give strong enhancement of the occupation of the S-state c.o.m. orbital of the α-particles. This is strong evidence that the state is regarded as the 4α condensed state. It also has a large component of [Formula: see text] configuration, which is another reliable evidence of the state to be of 4α condensate nature.

ALPHA CLUSTERING AND CONDENSATION IN 16O

2010 ◽  
Vol 25 (21n23) ◽  
pp. 1939-1942
Author(s):  
Y. FUNAKI ◽  
T. YAMADA ◽  
H. HORIUCHI ◽  
G. RÖPKE ◽  
P. SCHUCK ◽  
...  
Keyword(s):  
Excited State ◽  
Strong Evidence ◽  
The State ◽  
Orthogonality Condition ◽  
Condensed State ◽  
Density Structure ◽  
Condition Model ◽  
Strong Enhancement ◽  
Alpha Clustering ◽  
Α Particles

The α-particle condensed state in 16 O is investigated by the use of 4α OCM (Orthogonality Condition Model). Low-lying spectrum in experiment is well reproduced up to around the 4α break-up threshold. The excited state obtained around the 4α threshold as the [Formula: see text] state is shown to have a dilute density structure and give strong enhancement of the occupation of the S-state c.o.m. orbital of the α-particles. This is strong evidence that the state is regarded as the 4α condensed state.

DILUTE ALPHA-PARTICLE CONDENSATION IN 12C AND 16O

2008 ◽  
Vol 22 (25n26) ◽  
pp. 4545-4556
Author(s):  
T. YAMADA ◽  
Y. FUNAKI ◽  
H. HORIUCHI ◽  
A. TOHSAKI ◽  
G. RÖPKE ◽  
...  
Keyword(s):  
Alpha Particle ◽  
Equation Of Motion ◽  
Orthogonality Condition ◽  
Breakup Threshold ◽  
Hoyle State ◽  
Condition Model ◽  
Dilute Gas ◽  
Strong Candidate

Alpha particle condensation is studied in 12 C and 16 O with the orthogonality condition model (OCM). The OCM equation is an approximation of the equation of motion of α bosons based on microscopic theories. We demonstrate that 1) the Hoyle state (the [Formula: see text] state at 7.65 MeV in 12 C ), located just above the 3α disintegration threshold has a 3α-particle condensate character, in which 3α particles occupy an identical 0S orbit with 70 % occupancy, forming a dilute gas-like configuration, and 2) the [Formula: see text] state at Ex = 15.1 MeV in 16 O , appearing above the 4α breakup threshold, is a strong candidate with dilute 4α structure of the condensate-type.

CLUSTER STATES AND ALPHA PARTICLE CONDENSATION IN 13C

2008 ◽  
Vol 17 (10) ◽  
pp. 2101-2105 ◽  
Author(s):  
TAIICHI YAMADA ◽  
YASURO FUNAKI
Keyword(s):  
Alpha Particle ◽  
Cluster Model ◽  
Orthogonality Condition ◽  
Fair Agreement ◽  
Energy Spectra ◽  
Cluster States ◽  
Condition Model ◽  
Monopole Transition

The structure of 13 C is studied with the semi-microscopic cluster model, 3α+n orthogonality condition model (OCM). The energy spectra of four 1/2- states and three 1/2+ states up to Ex ~ 13 MeV are successfully reproduced, in particular, three monopole transition strengths are in fair agreement with the observed ones. We discuss the cluster states and alpha particle condensation in the 1/2± states appearing around the 12 C +n, 9 Be +α and 3α+n thresholds.

Alpha-particle decay of the 15∙1 MeV state in 12 C

1960 ◽  
Vol 259 (1297) ◽  
pp. 275-284 ◽  
Keyword(s):  
Alpha Particle ◽  
Resonance Scattering ◽  
The State ◽  
Particle Decay ◽  
Γ Ray ◽  
Break Up ◽  
Α Particles

A search was carried out for the α-particle decay of the 15∙1 MeV state in 12 C. The state was made by the 10 B ( 3 He, p ) 12 C reaction. The protons feeding the 15∙1 MeV state were seen in proton singles spectra and in coincidence with 15∙1 MeV γ -rays, but none were seen in coincidence with α -particles. Comparison with a nearby state known to decay virtually solely by α-particles established that the 15∙1 MeV state α -decays less than 20 % of the time. Combining this result with the results of γ-ray resonance scattering we find that ┌ α < 15 eV. The sensitivity of the experiment was limited by a continuum from the break-up of the 10 B + 3 He system.

Additive manufacturing of ceramics and cermets: present status and future perspectives

2021 ◽  
Author(s):  
Mainak Saha ◽  
Manab Mallik
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Present Status ◽  
Interdisciplinary Research ◽  
Low Density ◽  
Metallic Materials ◽  
Structure Property ◽  
Future Perspectives ◽  
Present Decade ◽  
Systematic Structure

The present decade has witnessed a huge volume of research revolving around a number of Additive Manufacturing (AM) techniques, especially for the fabrication of different metallic materials. However, fabrication of ceramics and cermets using AM-based techniques mainly suffers from two primary limitations which are: (i) low density and (ii) poor mechanical properties of the final components. Although there has been a considerable volume of work on AM based techniques for manufacturing ceramic and cermet parts with enhanced densities and improved mechanical properties, however, there is limited understanding on the correlation of microstructure of AM-based ceramic and cermet components with the mechanical properties. The present article is aimed to review some of the most commonly used AM techniques for the fabrication of ceramics and cermets. This has been followed by a brief discussion on the microstructural developments during different AM-based techniques. In addition, an overview of the challenges and future perspectives, mainly associated with the necessity towards developing a systematic structure-property correlation in these materials has been provided based on three factors viz. the efficiency of different AM-based fabrication techniques (involved in ceramic and cermet research), an interdisciplinary research combining ceramic research with microstructural engineering and commercialisation of different AM techniques based on the authors’ viewpoints.

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