Refine your search:     
Report No.
 - 
Search Results: Records 1-6 displayed on this page of 6
  • 1

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Positronium formation in fused quartz; Experimental evidence of delayed formation

Komuro, Yo; Hirade, Tetsuya; Suzuki, Ryoichi*; Odaira, Toshiyuki*; Muramatsu, Makoto*

Radiation Physics and Chemistry, 76(2), p.330 - 332, 2007/02

 Times Cited Count:3 Percentile:26.56(Chemistry, Physical)

Recently, positronium (Ps) formation mechanism in the spur is becoming clarified. Blob model, the modified Spur model, proposed by Stepanov can give information of Ps formation time. Dauwe et al. showed that S(t) curve of PMMA observed by AMOC measurement could be fitted by the blob model. The young-age broadening was found and explained with the delayed slowing down of Ps by Stuttgart group. The delayed Ps formation was shown by Suzuki et al. especially at low temperatures, because positrons can diffuse long distance to find trapped electrons. According to the blob model, Ps formation even after long diffusion of positrons might be possible even at the room temperature. Now we are trying to obtain the experimental evidence of delayed Ps formation in spur process.

Journal Articles

Positronium formation reaction of trapped electrons and free positrons; Delayed formation studied by AMOC

Suzuki, Naoki*; Hirade, Tetsuya; Saito, Fuminori*; Hyodo, Toshio*

Radiation Physics and Chemistry, 68(3-4), p.647 - 649, 2003/10

 Times Cited Count:23 Percentile:81.88(Chemistry, Physical)

no abstracts in English

Oral presentation

Development of AMOC system for measuring transient defects under irradiation

Ueda, Daisuke*; Konishi, Suzuka*; Minagawa, Hideaki*; Hirade, Tetsuya; Tsuchida, Hidetsugu*

no journal, , 

Damaged conditions under irradiation such as ion beams irradiation are transient and unstable. Understanding of this transient damage state is important to clarify the process from damage generation to stabilization. We are developing Age-MOmentum Correlation (AMOC) measurement system by $$beta$$$$^{+}$$-$$gamma$$ coincident measurement to investigate the triplet positronium (o-Ps) reactions as a probe of reactive species. From the correlation between "positron annihilation time" and "momentum of electron / positron at pair annihilation" obtained by AMOC measurement, it is possible to investigate the process of o-Ps reactions. We report on AMOC measurement system newly constructed by digital method.

Oral presentation

Development of $$beta$$$$^{+}$$-$$gamma$$ based AMOC measurement system

Konishi, Suzuka*; Ueda, Daisuke*; Xu, Q.*; Hirade, Tetsuya; Tsuchida, Hidetsugu*

no journal, , 

In order to elucidate the transient damage state by ion beam etc., positron annihilation lifetime - momentum correlation (Age-MOmentum Correlation: AMOC) apparatus by $$beta$$$$^{+}$$-$$gamma$$ simultaneous measurement is newly constructed by the digital method. In this study, we investigated the effect of $$gamma$$-irradiation of polystyrene using the AMOC apparatus. As a result, we obtained that the S parameter near 1 ns decreases corresponding to the increase of damage amount.

Oral presentation

Development of gamma-ray induced positron age-momentum correlation measurements at UVSOR-III

Yamamoto, Ryohei*; Sugita, Kento*; Taira, Yoshitaka*; Hirade, Tetsuya

no journal, , 

Age-Momentum Correlation (AMOC) can observe the Doppler broadening of time-resolved annihilation gamma rays. The annihilation rate depends on the positron state, and it is possible to know if positrons are trapped in structural defects in a sample. Moreover, the Doppler broadening gives the information of impurities around the defects. Positrons from radioactive isotopes cannot penetrate a deep region of bulk material. The application of radioisotopes is difficult for the measurements under severe conditions such as in high pressure or a high temperature. Therefore, we have developed a GiAMOC (Gamma-ray induced AMOC) system, which is a measurement method for generating positrons in a sample using inverse Thomson scattered gamma rays in UVSOR-III. In addition, the developed measurement system was used to measure the reference material for positron lifetime measurement.

Oral presentation

Positron annihilation age momentum correlation (AMOC) measurement

Hirade, Tetsuya

no journal, , 

Positron annihilation Age-MOmentum Correlation (AMOC) measurement is the coincidence measurement method of positron injection time, positron annihilation time and positron annihilation gamma-rays energy. The methods for measurement and analysis of AMOC will be introduced briefly. Some of the interesting researches also will be introduced.

6 (Records 1-6 displayed on this page)
  • 1