Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Kokubu, Yoko; Matsubara, Akihiro; Miyake, Masayasu*; Nishizawa, Akimitsu*; Owaki, Yoshio*; Nishio, Tomohiro*; Sanada, Katsuki*; Hanaki, Tatsumi
Nuclear Instruments and Methods in Physics Research B, 361, p.48 - 53, 2015/10
Times Cited Count：14 Percentile：75.23(Instruments & Instrumentation)The JAEA-AMS-TONO facility was established in 1997 at the Tono Geoscience Center, Japan Atomic Energy Agency. Our AMS system has been made available for 
C- and 
Be-AMS. At present, the development of 
Al-AMS has been conducted to enhance the capability for multi-nuclide AMS. In this presentation, we report the progress on multi nuclide AMS in addition to the status of our facility.
E counterMatsubara, Akihiro; Miyake, Masayasu*; Nishizawa, Akimitsu*; Kokubu, Yoko
no journal, ,
The effect of isobar (B ions) interference on the pulse trace was investigated with the E counter for Be-AMS. To make the B overload, the gas pressure, 
, of the passive absorber cell located in front of the E counter is reduced from 62 Torr to 32 Torr. It is found that as is reduced less than 54 Torr, the width of baseline fluctuation, 
, of the Be pulse trace respective to E increases several times. The energy loss for the B ion, E
, calculated by SRIM shows that behavior of both E and is very similar. The baseline fluctuation can be attributed to the remaining positive charge by the B overload. If some instability exists in the charge accumulation and/or loss system, the anode potential can fluctuate around its equilibrium value. Volumetric ion-electron recombination would be a candidate for the instability.
Suzuki, Takashi; Otosaka, Shigeyoshi
no journal, ,
no abstracts in English
Okuno, Mitsuru*; Wada, Keiji*; Torii, Masayuki*; Danhara, Toru*; Nakamura, Toshio*; Kokubu, Yoko; Gualtieri, L.*; Brenn, S.*
no journal, ,
Adak Island, a member of the Andreanof Islands in the Aleutian Islands, Alaska is covered with Holocene sequences of soil-tephra complexes. Tephra layers are useful for establishing a chronographic framework on the island. Black (1976) described the three conspicuous tephra deposits (Main, Intermediate and Sandwich in ascending order). In order to re-evaluate the chronological framework, we conducted AMS radiocarbon dating and petrographic analysis on cored peat deposits collected from near Haven Lake. Charcoal fragments collected from around Three Arm Bay, southwestern area, are also dated. This poster presents petrography and radiocarbon dates. Based on our results, eruption ages of the Main, Intermediate, Sandwich, YBO and Forty Yeartephra were dated to approximately 9.5, 7.2, 4.7, 3.6 and 0.4 cal ka BP, respectively.
Minami, Masayo*; Takahashi, Hiroshi*; Aramaki, Takafumi*; Kokubu, Yoko; Ito, Shigeru*; Wada, Hideki*; Nakamura, Toshio*
no journal, ,
We generally use some sample preparation methods for radiocarbon analysis of dissolved inorganic carbon (DIC) in water samples; the precipitation method, the bubbling method and the headspace-extraction method. These sample preparation methods have good and bad points each. Therefore, we have initiated a Radiocarbon Intercomparison on Chemical Experiments, Water series (RICE-W) program in Japan to examine whether the CO
extraction procedures of water DIC introduce carbon isotopic fractionation and carbon contamination. Eight water samples for four kinds of surface seawater, ground water, hot spring water, and sodium bicarbonate solution have already provided to six AMS laboratories in Japan and are being carried out comparison of C measurements. We show the result of the RICE-W program in this presentation.
