scholarly journals Stability of a New, Multichannel, Low-Level Liquid Scintillation Counter System, Kvartett

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 727-736 ◽  
Author(s):  
Sigurđur Einarsson ◽  
Páll Theodórsson
Keyword(s):  
Count Rate ◽  
Liquid Scintillation ◽  
Scintillation Counter ◽  
Counting System ◽  
Background Count ◽  
Background Count Rate ◽  
Low Level ◽  
Quality Control Standard ◽  
Conventional Systems ◽  
Sample Vial

Kvartett is a new liquid scintillation counting (LSC) system for radiocarbon dating that takes a radical departure from conventional systems to obtain a compact, low-level counting system measuring four samples simultaneously. Each sample vial, inside the well of a large NaI(Tl) guard-counter crystal (facing down), sits on top of a vertical PMT. The fourfold counting capacity can be used to increase the number of samples being dated or to get higher precision. The increased throughput helps to keep a rigid quality-control standard. We monitored the background count rate almost continuously for 7 months, and measured the count rate of a standard repeatedly for 2 months. The results show the background and system reproducibility to be stable.

scholarly journals Performance of the Packard 2000 CA/LL and 2250 CA/XL Liquid Scintillation Counters for 14C Dating

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 352-358 ◽  
Author(s):  
G T Cook ◽  
D D Harkness ◽  
Robert Anderson
Keyword(s):  
Count Rate ◽  
Liquid Scintillation ◽  
Scintillation Counter ◽  
14C Dating ◽  
Background Count ◽  
Background Count Rate ◽  
Low Level ◽  
On Line ◽  
Guide System ◽  
Careful Manipulation

Results are presented on the comparative characteristics of the Packard 2000 CA/LL liquid scintillation counter with and without the low-level option on line. An initial performance assessment using 14C labeled benzene with butyl-PBD as the scintillant revealed that although the background count rate decreased by approximately a factor of 3 using the low-level option, a substantial decrease in efficiency was also observed. However, subsequent investigations have indicated that, by careful manipulation of both scintillant composition and concentration, this loss in efficiency can largely be overcome with little or no concurrent increase in background count rate. The introduction of an active vial sample holder and a new light-guide system proved to be significant advances on the standard 2000 CA/LL.

scholarly journals Newly Designed 0.8-ML Teflon® Vial for Microvolume Radiocarbon Dating

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 743-747 ◽  
Author(s):  
Michael Buzinny ◽  
Vadim Skripkin
Keyword(s):  
Significant Influence ◽  
Count Rate ◽  
Radiocarbon Dating ◽  
Figure Of Merit ◽  
Liquid Scintillation ◽  
Detection Efficiency ◽  
Operational Parameters ◽  
Counting Period ◽  
Background Count ◽  
Background Count Rate

We have tested two versions of an 0.8-ml volume Teflon® vial, designed specifically for radiocarbon dating in the microvolume range, using a modern Quantulus 1220™ liquid scintillation (LS) spectrometer. We determined the counting performance of each vial type in conjunction with different designs of copper holder, viz., with and without the incorporation of a “Teflon® light coupler”. We also compared the losses of sample benzene during a typical 28-day counting period. Results show that neither vial design nor the type of vial holder used in the intercomparison had a significant influence on counting performance. We recorded an absolute 14C detection efficiency of 82% against a background count rate of 0.1 cpm, i.e., a “figure of merit (FM) value” = 67,240. This compares favorably with the operational parameters anticipated for microvolume 14C dating by modern LS spectrometry. However, variations in the design of the sealing method used between the vial types was reflected in an apparent approximate tenfold difference in the amount of benzene lost during routine counting. In the better case, the evaporation loss was equivalent to 0.032 mg of benzene per day.

scholarly journals The Potential of the London Underground for Liquid Scintillation Counting

Radiocarbon ◽  
1986 ◽  
Vol 28 (2A) ◽  
pp. 592-596
Author(s):  
Sheridan Bowman
Keyword(s):  
Count Rate ◽  
Liquid Scintillation ◽  
Cosmic Ray ◽  
Gamma Spectrometer ◽  
Background Count ◽  
Background Count Rate ◽  
Low Potassium ◽  
London Underground ◽  
Order Of Magnitude ◽  
Cosmic Ray Flux

A portable gamma spectrometer has been used to survey three locations that are part of the London Underground Transport System (the “tube”). Up to an order of magnitude reduction in the cosmic ray flux was observed relative to the laboratory level. The likely reduction in background count rate achievable by underground siting of currently used Packard and LKB liquid scintillation counters is considered. It is noted that in the present, surface usage for radiocarbon dating, the background count rate of low-potassium glass vials in the LKB is not substanially higher than that of PTFE vials.

scholarly journals Dublin Radiocarbon Dates II

Radiocarbon ◽  
1974 ◽  
Vol 16 (1) ◽  
pp. 6-9 ◽  
Author(s):  
P Q Dresser ◽  
I R Mcaulay
Keyword(s):  
Count Rate ◽  
Radiocarbon Dating ◽  
Detection Efficiency ◽  
Scintillation Counter ◽  
Barometric Pressure ◽  
Electronic Equipment ◽  
Background Count ◽  
Background Count Rate ◽  
Radiocarbon Dates ◽  
Silica Cell

The Dublin radiocarbon dating laboratory was operational in 1958 to 1960 and the scintillation counter system used at that time has previously been described (Delaney and McAulay, 1959). The system is now operational again and has been modified to date samples after conversion to benzene. The electronic equipment differs from that previously used only insofar as more compact and drift-free transistorized units are now employed. With these modifications, considerable improvements in sensitivity and accuracy are obtained. 5ml benzene, diluted with a commercial toluene based scintillant is used in a 12.5ml silica cell for the detection of 14C disintegrations. The background count-rate varies inversely with the barometric pressure (ca 2.6% cm–1Hg). The background is ca 3.4cpm, and the detection efficiency is ca 60% and excludes the tritium spectrum.

scholarly journals Time-Resolved Liquid Scintillation Counting

Radiocarbon ◽  
1990 ◽  
Vol 32 (3) ◽  
pp. 381-386 ◽  
Author(s):  
Michael Kessler
Keyword(s):  
Spectrum Analysis ◽  
Liquid Scintillation ◽  
Scintillation Counter ◽  
Counting Efficiency ◽  
General Purpose ◽  
Scintillation Counting ◽  
Age Dating ◽  
Time Resolved ◽  
Low Level ◽  
Special Time

Historically, scientists who perform low-level measurements of 14C for age dating, and 3H2O for environmental contamination, have purchased or constructed highly specialized instruments to quantitate low-level radionuclides using a general-purpose liquid-scintillation analyzer (LSA). The LSA uses special time-resolved 3-D spectrum analysis (TR-LSC) to reduce background without substantially affecting sample counting efficiency. This technique, in combination with a special slow fluor scintillating plastic, further reduces the minimal detectable limit for the TR-LSC liquid scintillation counter.

scholarly journals A Beta Test Comparison Between the New Packard 2260 XL and the LKB Quantulus and 1219 SM: Low-Level Radiocarbon and Tritium Determinations

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 368-373 ◽  
Author(s):  
Robert M Kalin
Keyword(s):  
Test Performance ◽  
Liquid Scintillation ◽  
Scintillation Counter ◽  
Liquid Scintillation Counter ◽  
Low Level ◽  
Counting Chamber ◽  
Beta Test

A Packard 2260 XL liquid scintillation counter was placed in an underground counting chamber to test performance under immense physical shielding. Results from the Packard 2260 XL are compared with two other counters under the same conditions, the LKB Quantulus, which has operated for two years in this laboratory, and the LKB 1219 SM, in use since January 1988.

scholarly journals Low Background Liquid Scintillation Counting Using an Active Sample Holder and Pulse Discrimination Electronics

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 332-341 ◽  
Author(s):  
John E Noakes ◽  
Robert J Valenta
Keyword(s):  
Experimental Data ◽  
Liquid Scintillation Counting ◽  
Liquid Scintillation ◽  
Background Radiation ◽  
Scintillation Counting ◽  
Sample Holder ◽  
Counting System ◽  
Low Background ◽  
Low Level ◽  
Beta Counting

A Packard low-level liquid scintillation counting system is described which provides superior low-background beta-counting capability for3H and14C. The design is based on a novel pulse-discrimination circuit that separates background from valid scintillation pulses. Background discrimination is further enhanced by adding a plastic vial holder that acts as an anticoincidence guard. When excited by background radiation, the scintillation properties of the plastic provide an increased burst of photons to the detection electronics, which discriminate based on the number of component pulses in the burst. Experimental data demonstrate the low-level counting capabilities of this counter.

scholarly journals Determination of 14C in Alcoholic Beverages

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 777-784 ◽  
Author(s):  
Franz Schönhofer
Keyword(s):  
Lower Limit ◽  
Liquid Scintillation ◽  
Limit Of Detection ◽  
Scintillation Counter ◽  
Age Determination ◽  
Alcoholic Beverages ◽  
Quick Method ◽  
Low Level ◽  
Factors Influencing

A simple and quick method for the determination of 14C in ethanol has been developed, using an ultra low-level liquid scintillation counter. I have studied factors influencing the lower limit of detection and have shown that liquor can be measured directly without pretreatment. Results of measurements on Austrian wines are presented and compared with results obtained from tritium measurements. The applicability and limitations of the results to age determination are discussed.

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