High Counting Efficiency Research Articles

Exploring the filtration performance and usage cost of commercial fiber air filters for capturing moxa smoke aerosols

Traditional moxibustion treatments plays a role in preventing and treating COVID-19 while aggravating indoor air pollution. Therefore, commercial fiber air filters (CFAF) are widely used to improve indoor air quality to reduce the risk of people being exposed to moxa smoke aerosols (MSA). Considering that there were few reports on the performance of CFAF for capturing MSA, we explored in detail the effects of face velocity and MSA particle size on the filtration performance of CFAF to fill this gap. Then, we analyzed the deposition characteristics of MSA on fibers in combination with SEM images. In addition, the long-term stability, cleaning performance and MSA holding capacity of the CFAF were further characterized by tests of continuous operation, clean air delivery rate (CADR) and MSA loading. The results indicated that the CFAF had the potential to efficiently capture MSA in indoor air at an acceptable annual usage cost (AUC). Specifically, the pristine CFAF had high classification counting efficiency (CCE) (99.1 %-100 %), medium pressure drop (150.3 Pa), and low quality factor (0.04 Pa−1) at the face velocity of 0.3 m·s−1. Note that increasing face velocity not only decreased CCE and quality factor but also significantly increased pressure drop. Furthermore, the CFAF maintained excellent CCE (99.5 %-100 %) after 24-h of continuous operation at high concentrations of MSA (100 mg·m−3), while the pressure drop increased to 203.7 Pa. Obviously, the deposited MSA severely clogged the inter-fiber pores, which explained the fact of the rapid increase in the pressure drop of the CFAF. Of course, the high CADR value (66.6 m3·h−1) also demonstrated that the CFAF had the ability to efficiently remove MSA from confined place. Moreover, a total of 216.3 g MSA can be captured by the CFAF when the final pressure drop reached 300 Pa, which meant that further increasing the MSA holding capacity would be the focus of future research by filter media manufacturers. Finally, through the established mathematical model, we successfully predicted the service life (86 days) and the total AUC (276 $·year−1) of using the CFAF to capture MSA. This work is expected to provide a useful reference for routine maintenance and design optimization of existing CFAF.

Design of a high counting efficiency sensor for 1.0 cubic feet per minute laser particle counter.

Based on the theory of Mie scattering, an optical sensor for a 1.0 cubic feet per minute laser particle counter is developed in this paper. First, an illumination optical path relying on aspherical lens and cylindrical lens for laser shaping was designed, and a narrow optical spot with the illumination in the vertical direction of the photosensitive area approximately distributed as a flat top was obtained. Second, the scattering light path was designed by using the theory of Mie scattering and geometric optics method. Then, the structure of the sampling air path was designed with reference to the principle of Laval nozzle, and the particle flow trajectory was verified by simulation using the fluid dynamics software Ansys Fluent. Finally, the performance of the optical sensor was measured with polystyrene latex (PSL) particles, and the results showed that the counting efficiency of the 0.3μm particle size channel met the requirement of 50% ± 20% and the 0.5μm particle size channel met the requirement of 100% ± 10%, which complied with the ISO 21501-4 standard.

Development and Application of Particle Transport Monte Carlo Simulation Modeling Toolkit

In particle transport Monte Carlo simulation, the manual modeling method is not suitable for complex geometric models. A Monte Carlo Simulation Modeling Toolkit (pyMCMT) is developed based on Python language. The toolkit can generate input card in several classical format such as MCNP and GDML format automatically. In this paper, two typical applications are presented based on the pyMCMT toolkit: 1, constructing a multilayer circular geometric model in complex density distribution by pyMCMT toolkit in order to satisfy the requirement of building large-space fine model with the influence of blast wave. A two-dimensional adaptive model is built for non-uniform atmospheric induced by blast wave. The number of the cells in this model is reduced vastly with the same model resolution; 2, producing the optimized weight window parameter using the mesh-based weight window variance reduction combined with density iteration method which is realized to solve the high statistical fluctuation and low counting efficiency problem in deep penetration process. The successful application of pyMCMT shows that pyMCMT is a modularized, parameterized, customizable and easy-to-debug toolkit for particle transport Monte Carlo simulation modeling, which can improve the modeling efficiency tremendously.

Toward a simplified calibration method for 23 nm automotive particle counters using atomized inorganic salt particles

In 2011, the Euro 5b light-duty vehicle legislation introduced particle number (PN) limits for vehicle homologation. To measure PN concentrations, specific condensation particle counters (CPC) with a counting efficiency (CE) of 50% at 23 nm are required. The usage of such automotive CPCs will significantly increase with the upcoming legislation for PN measurements during periodic technical inspections, which comes along with the need for simple calibration methods for particle number counters using salt particles. In this work, we examined the counting characteristics of an automotive AVL 23 nm CPC with inorganic salt particles. We further investigated the usability of different atomized inorganic salt particles for calibration purposes focusing on CE and linearity. The CE varies greatly depending on the chemical salt composition: While NaI was fully activated down to 18 nm and linear over the full concentration range, the CE of other atomized salt solutions showed a strong concentration dependency with a d50 diameter ranging from 38.2 nm to 69.5 nm for atomized NaCl with increasing concentration. Such effects were not found for tube-furnace generated salt particles within similar concentration ranges. When a hot dilution was applied, the non-linear behavior was minimized and the CE overall increased, leading to a d50 of 27.3 nm for atomized NaCl. Based on those findings, we propose a simplified calibration method for automotive PN counters without the need for a differential mobility analyzer due to the high CE of atomized NaI particles.

Delayed neutron counting of uranium pins using moderated neutrons from portable DD neutron generator in high frequency mode

Delayed neutron counting is often used to verify the characteristics of nuclear material. Use of portable neutron generators in high frequency pulsing mode enables effective analysis with higher counting efficiency and lower radiation protection demands. The paper deals with delayed neutron counting of uranium pins with P385 portable DD neutron generator in polyethylene-based setup. Counting is performed in high frequency mode of neutron generator. The viability of such measurement in the frequency range from 100 Hz to 250 Hz was demonstrated and optimal pulsing parameters for P385 neutron generator were found. Delayed neutron counting was then performed for two types of uranium rods. Delayed neutrons were counted both inbetween neutron pulses during neutron generation and once the emission of neutrons stopped. The results were further validated by Monte Carlo (MCNP) simulations. For the geometry of studied rods, the MCNP calculation were done to calculate the dependence of the response to delayed neutrons on rod enrichment, to show the viability to use the method for rod enrichment verification. An option of using cadmium inset in irradiation channel to overcome the effect of self-shielding for samples with higher enrichment was proposed, experimentally tested, and evaluated through MCNP calculations.

Assessment of natural radioactivity and its radiological hazard in some decorative materials in Iraq

Most buildings use decorative materials that are aesthetically pleasing, that may contain various amounts of radioactive elements. Thus, the human health of dwellers and workers is continuously exposed to ionizing radiation. Natural radioactivity (238U, 232Th, and 40K) is measured in decorative materials collected from different Iraqi local markets by utilizing a shielded high counting efficiency NaI(Tl) system. Some radiological hazard indexes in all samples were calculated. The results obtained showed that the maximum value of specific activity for 238U, 232Th, and 40K is in decorative stone and the minimum is measured in decorative alabaster. This study concluded that the natural radioactivity and radiological hazard in most samples of decorative materials were within the permissible limits by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), the International Commission on Radiological Protection (ICRP), Organization for Economic Co-operation and Development (OECD), and other world reported. Therefore, most samples of decorative materials in the present study can be used without health risks according to radiation scope.

Development of 222Rn Emanation Sources with Integrated Quasi 2π Active Monitoring.

In this work, a novel approach for the standardization of low-level 222Rn emanation is presented. The technique is based on the integration of a 222Rn source, directly, with an α-particle detector, which allows the residual 222Rn to be continuously monitored. Preparation of the device entails thermal physical vapor deposition of 226RaCl2 directly onto the surface of a commercially available ion implanted Si-diode detector, resulting in a thin-layer geometry. This enables continuous collection of well resolved α-particle spectra of the nuclei, decaying within the deposited layer, with a detection efficiency of approximately 0.5 in a quasi 2π geometry. The continuously sampled α-particle spectra are used to derive the emanation by statistical inversion. It is possible to achieve this with high temporal resolution due to the small background and the high counting efficiency of the presented technique. The emanation derived in this way exhibits a dependence on the relative humidity of up to 15% in the range from 20% rH to 90% rH. Traceability to the SI is provided by employing defined solid-angle α-particle spectrometry to characterize the counting efficiency of the modified detectors. The presented technique is demonstrated to apply to a range covering the release of at least 1 to 210 222Rn atoms per second, and it results in SI-traceable emanation values with a combined standard uncertainty not exceeding 2%. This provides a pathway for the realization of reference atmospheres covering typical environmental 222Rn levels and thus drastically improves the realization and the dissemination of the derived unit of the activity concentration concerning 222Rn in air.

Experimental and simulated methods to characterize the response of a scintillator detector

The NaI(Tl) detector is one of the most used in gamma ray spectrometry because it presents high counting efficiency for gamma rays in a wide energy range. This study presents the modeling of a real 1¼ x ¾" NaI(Tl) scintillation detector + photomultiplier using computational simulations carried out by the MCNP6 code, which considers energy resolution. In the mathematical model, the sensitive volume of the detector was adjusted using 241Am and 137Cs radiation sources by means of the absolute photopeak efficiency. Moreover, the MCNP6 code was used to calculate the effective solid angle of the detector in order to obtain the intrinsic efficiency response function. The mathematical model was experimentally validated using calibrated radioactive sources (241Am, 133Ba, 137Cs and 60Co) and the response functions - efficiency curve and energy resolution - were obtained. In addition, an experimental evaluation of the crystal homogeneity of the detector was made using a137Cs radiation source and a 3D printed device developed without stepper motors. The proposed methodology is able to obtain absolute photopeak efficiency in agreement with experimental data with maximum relative error of 5.64%. The gamma scanning procedure indicated that the crystal of the detector remained homogeneous.

Feasibility of Prompt Gamma Ray Detection and Imaging Using CdTe Detectors for BNCT ― Monte Carlo Study

Boron neutron capture therapy (BNCT) has experienced a renaissance in recent years, due to the availability of accelerator-based neutron sources and more effective delivery vehicles of boron-10 (10B). For successful BNCT, 10B concentration and distribution in the tumor (as well as in the critical organs) must be determined non-invasively prior to BNCT treatments. While conventional nuclear imaging (e.g., PET/SPECT), in conjunction with radiolabeled 10B, may serve for this purpose, another approach, based on the detection of prompt gamma (PG) rays from the BNC reaction, appears to be more attractive, most notably because it can be implemented within the BNCT setup without radiolabeling of 10B. The detectability of PG rays (478 keV) from the BNC reaction has been shown experimentally within the context of BNCT utilizing energy-resolving solid-state detectors. However, the feasibility of this approach under the clinically relevant conditions is currently unknown. Thus, the present work investigated this feasibility by performing Monte Carlo (MC) simulations using the simulation toolkit.MC models of various phantom cases were created to simulate epithermal neutron beam irradiation relevant to accelerator-based BNCT (a-BNCT). For benchmarking and future experimental verification, the phantom geometry (20 cm-diameter/24 cm-height cylinder) and material (PMMA) were chosen based on a published experimental study. The phantom had 3 cm-diameter/3.8 cm-height cylindrical inserts (located at 5 cm depth along the long-axis of the phantom) that contained 10B solution at different concentrations ranging from 1 - 30,000 parts-per-million (ppm). For detection of PG rays, a 23.1 cm-diameter ring detector consisting of 120 cadmium telluride (CdTe) crystals was modeled. CdTe was chosen because of its high photon counting efficiency and energy resolution. Each CdTe detector crystal (5 × 5 × 1 mm3) contained an inherent 0.1mm-thick beryllium window and a novel/custom thermal neutron filter made of gadolinium. Two billion incident neutron histories were used during each MC simulation. The detected PG ray signals were used to test both direct mapping and CT techniques for quantitative imaging.The current MC simulations showed PG ray signals from the10B-loaded tumor-mimicking cylindrical insert were above the background noise (with a 95% confidence level), down to the clinically achievable tumor 10B concentration of 30 ppm. The custom thermal neutron filter was effective in suppressing the inherent background from CdTe detectors.This MC study demonstrated the detectability of PG rays from the BNC reaction using CdTe detectors under the conditions closely mimicking realistic a-BNCT scenarios. It also showed that clinically acceptable quantitative imaging of 10B distribution could be performed utilizing the PG ray signals from the BNC reaction.H. Moktan: None. C. Lee: None. S. Cho: Research Grant; TAE Life Sciences.

Use of the Grubbs test to study the homogeneity of a NaI(Tl) detector

The NaI(Tl) detector is one of the most used in gamma ray spectrometry because it presents high counting efficiency for gamma rays in a wide range of energy. The crystal can have a lower efficiency that can be indicated by the effects of its aging by several factors such as: the reaction of sodium iodide with magnesium oxide, absorption of water vapor by crystal, and problems related to photomultiplier. In an experiment, several measures can be take and when a doubt exists between one of the measured values it is possible to use a statistical test. Grubbs test is designed to verify the presence of extreme values in sample observations. This paper presents a methodology that has the objective of evaluating the homogeneity of a NaI(Tl) scintillation detector using the Grubbs test to validated the crystal homogeneity. The study pre-established five differents locations in frontal area of detector where measurements were performed using a 137Cs standard source in order to calculate the standard deviation.

Development of a fast characterization setup for radionuclide generators demonstrated by a 227Ac-based generator

Abstract The development of a setup for a fast online characterization of radionuclide generators is reported. A generator utilizing the mother nuclide 227Ac sorbed on a cation exchange resin is continuously eluted by using a peristaltic pump. To allow continuous and pulse-free elution of a large volume over extended time periods a 3D-printed interface designed to remove pressure-oscillations induced by the pump was placed between pump and generator column to ensure undisturbed generator elution. The eluate of the generator is passed through a 3D printed flow cell placed inside a borehole Na(Tl)-scintillation detector for high counting efficiency. Alternatively, a HPGe detector suitable for nuclide identification was used to demonstrate the validity of the online method. The detection system combines conventional gamma-ray spectrometry with fast list mode data acquisition in the Matlab software package. Elution experiments were performed at different flow rates of hydrochloric acid, separating 211Bi (t 1/2 = 2.14 min) free from its parent nuclides. In addition, to prove the versatility of the setup, experiments at different hydrochloric acid concentrations were performed resulting in the elution of pure 211Pb (t 1/2 = 36.1 min) and 223Ra (t 1/2 = 11.43 d), respectively.

Assessment of nuclear radiation pollution in uranium mining-impacted soil

Activities associated with mining of uranium have generated significant quantities of waste materials containing uranium and other toxic metals. A qualitative and quantitative study was performed to assess the situation of nuclear pollution resulting from waste of drilling and exploration left on the surface layer of soil surrounding the abandoned uranium mine hole located in the southern of Najaf province in Iraq state. To measure the specific activity, twenty five surface soil samples were collected, prepared and analyzed by using gamma- ray spectrometer based on high counting efficiency NaI(Tl) scintillation detector. The results showed that the specific activities in Bq/kg are 37.31 to 1112.47 with mean of 268.16, 0.28 to 18.57 with mean of 6.68 and 132.25 to 678.33 with mean of 277.49 for 238U, 232Th and 40K respectively. Based on these values, radium equivalent activity in Bq/kg and absorbed dose rate one meter above the ground surface nGy/h were calculated and found to be vary 52.72 to 1189.84 and from 25.02 to 553.01. The indoor and outdoor annual effective dose rate in mSv/y ranged from 0.12 to 2.71 and from 0.03 to 0.67 respectively. To evaluate the dangerous of the study area, the external (Hex) and internal (Hin) hazard indexes are calculated and found to be ranged 0.14 to 3.21 and from 0.24 to 6.22. For the purpose of assessing the seriousness of the study area, results were compared with the world wide average. This comparison indicated that the study area is not safe from the radiological protection point view.

Study of radiotoxic 210Po in Indian tobacco using liquid scintillation spectrometry

Abstract A fast radioanalytical method has been developed to measure 210Po in tobacco samples. After microwave digestion polonium is extracted quantitatively from a 1 M hydrochloric acid solution into a solution of triisooctylamine in toluene. The extract was measured by liquid scintillation counting in α mode. Caused by the high counting efficiency the counting time per sample can be reduced significantly compared to conventional α spectrometry, allowing for high sample throughput. The method was applied to 11 brands of cigarettes, beedis and or chewing tobaccos from India. Based on the resulting activity concentrations and typical consumption habits, annual and lifetime equivalent doses were calculated. They were found to be ~100–700 μSv/a or ~5–35 mSv, respectively.

Characteristic X-ray detector with a large sensitive area: Its sensitivity to environmental radioactive cesium and imaging performance as confirmed in an area of Fukushima

An X-ray detector which we call the characteristic X-ray detector (CXRD) with a large sensitive area of 199 cm2 was studied as a candidate imaging device with high sensitivity, light weight and low-cost features to visualize environmental 137Cs deposited after the Fukushima Dai-ichi Nuclear Power Station accident. The CXRD has a directionality for its sensitivity and it is able to visualize a spatial distribution of 137Cs by scanning the flux of 32 keV characteristic X-rays due to disintegration of 137Cs instead of imaging the 662 keV gamma-rays from 137Cs. Our experimental results showed that the counting efficiency of the CXRD was 105 counts per second for a 1 MBq 137Cs source at a distance of 1 m and the CXRD had a very high counting efficiency for a certain direction. We estimated the potential sensitivity of the CXRD when it was used in the scanning mode to image an area of 2π sr. The CXRD was tested in a contaminated forest in Fukushima Prefecture and images of the spatial distribution of 137Cs in the forest were successfully obtained. We found that most of the 137Cs was present in the forest floor and no 137Cs was detected in the atmosphere and the tree canopy. The CXRD is useful because of its low cost, light weight and high sensitivity as a 137Cs imaging device for monitoring post devices in forests and as a portable imaging device to confirm the effectiveness of decontamination work.

Simple Method for High-Sensitivity Determination of Cosmogenic 35S in Snow and Water Samples Collected from Remote Regions.

Cosmogenic 35S is useful in understanding a wide variety of chemical and physical processes in the atmosphere, the hydrosphere, and the cryosphere. The 87.4-day half-life and the ubiquity of sulfur in natural environments renders it an ideal tracer of many phenomena. Measurements of 35S in snow and water samples are scarce as existing analytical methods require a large volume of sample (>20 L) due to their high analytical activity background and low counting efficiency. Here, we present a new set of snow/water sample collecting and handling procedures for high-sensitivity determination of cosmogenic 35S using a low-level liquid scintillation spectrometer. Laboratory experiments using diluted 35S standards (with activities of <5 disintegrations per minute) showed a 35S recovery percentage of ∼95%, demonstrating a relatively small deviation from the true value. Using this method, we successfully measured 35S in ∼1 L of fresh snow sample collected from a glacier on the Tibetan Plateau to be 47 ± 7 mBq/L. On the basis of 35S activities in 9 natural samples measured in this study, a first proof-of-concept approximation for age determinations and source attributions was presented. This new method will provide a powerful tool in studying 35S in small volumes of snow and water samples, especially those from remote but climatically important regions such as the polar regions and the Tibetan Plateau and Himalayas. The measurements are particularly important as the radioactive sulfur provides an actual clock of glacial melting processes. With the growing rate of glacial loss, the need for measurements from remote locations becomes all the more important.

METHODOLOGY FOR THE ASSESSMENT OF INGESTED ACTINIDES FROM MONTE CARLO SIMULATION OF VOXEL PHANTOM

In case of internal contamination of actinides by ingestion pathway, activity will be transferred to various regions of the alimentary tract over a period of time. In this article, counting efficiencies (CEs) of Phoswich and an array of HPGe detectors are estimated for source in alimentary tract of voxel phantom. The phantom as well as Phoswich, and an array of three HPGe detectors are incorporated in Monte Carlo code 'FLUKA'. Human alimentary tract model is solved using default parameters to identify different compartments where activity will accumulate after an ingestion intake of 1 Bq as a function of time. Accordingly, CEs are evaluated on 0.5-5 d post ingestion intake for the source distributed in the contents of alimentary tract for photon energies in 18-238 keV range representing sources of actinides. The assessment of ingested activity of actinides from abdomen measurements is discussed. Higher CEs are observed with Phoswich detector compared with HPGe array due to its large size and high effective Z. Also, the CEs observed on Days 1-5 using both the detectors are found to decrease by 16-75 % with respect to the CE on half day. Thus, there is need to use CEs according to the observed activity distribution post ingestion intake. The contribution in the abdomen measurements due to source in the lungs and vice versa is also studied for intake by both inhalation and ingestion pathways. The contribution of source in the liver is found to be ∼30-50 % in chest and 75 % in abdomen measurements.

Activity measurement of 68Ge–68Ga by use of 4π(β++γ) integral counting method

A 4π(β++γ) integral counting method using 4πβ–4πγ detector configuration composed of a large well type NaI(Tl) scintillation detector and stacked plastic scintillators positioned in the center of the well and coupled with a slender PMT was adopted for activity measurement of 68Ge–68Ga. Several source preparation schemes were studied to reduce the activity loss due to volatility. The possible contribution of EC events were rejected with pulse-height discrimination. Owing to the high counting efficiencies in both channels and the multiplicity of photons and β-particles emitted, the 4π(β++γ) integral counting system gives a count rate very nearly equal to the positron emission rate. The activity can be determined simply from this value divided by the positron emission branching ratio. The remaining overall inefficiency was evaluated by the EGS5 code.

Reference drums used in calibration of a plastic scintillation counter in a 4π counting geometry

In this study, two kinds of reference drums were developed. One type was constructed with nine layers of large-area sources filled with different materials having five different densities. The other type of reference drums was constructed with nine rod sources filled with the same materials of different densities. The efficiency calibration of a plastic scintillation counter in 4π counting geometry using these two kinds of drums showed that rod-source drums resulted in higher counting efficiency than layered source drums. The counting rates obtained from rod-source drums were closer to those obtained from a standard drum with water solution than counting rates from drums with layered sources. The results of this study recommend to use reference drums with rod-sources to compensate the drawbacks of standard drums with water solution of not being able to adjust the density of material. The proposed reference drums improve the accuracy of radioactivity analysis for waste drums of different densities.

Flow cytometric quantification of viruses in activated sludge

Viruses may play a critical role in the microbial dynamics of activated sludge systems; however the difficulty of their quantification makes long term and large scale studies costly, timely and challenging. Thus a flow cytometric protocol was optimised and employed to determine virus abundance in activated sludge samples. The best flow cytometry signature and highest virus count was obtained by separating the indigenous floc-associated viruses using Tween 80 and sodium pyrophosphate, diluting the sample with Tris–EDTA and staining with SYBR Green II. Using the optimised protocol viral concentrations from 25 activated sludge plants were determined, with average concentrations of 2.35 × 109 mL−1 observed. Direct counts by transmission electron microscopy were highly correlated with flow cytometric counts (p = <0.05 and r2 = 0.77), with concentrations from both quantification methods comparable at the order of magnitude level. The high counting efficiency, ease of preparation and rapidity and reproducibility of analysis makes flow cytometric quantification of viruses in activated sludge ideal for routine investigation and thus invaluable in unravelling the complexity of phage host interactions in such systems.

Comparison study on characteristics of nano-sized particle number distribution by using condensation particle counter calibrated with spray and soot type particle generation methods

In the year 2011, the Particle Measurement Program (PMP) in Europe started the regulation of the diesel vehicle’s nano-sized particle number density (PN) due to its high degree of harm to the human body. Concretely, the standard level of PN emission was introduced in the Euro 5+ and 6 emissions regulation with a limit (<6.0 × 1011#/km) for diesel light-duty vehicle. Therefore, the determination of suitable and sophisticated instruments for reliable particle sampling and analysis was essential in taking exact experimental data. Now, among the PN emission measuring devices suggested by the PMP, condensation particle counter (CPC) is a key equipment for measuring the particle number density in real time and it has been used extensively. However, CPC can cause different results depending on operating conditions of the saturator and condensation that induce different rates of particle growth. This study was conducted to analyze the effect of CPC calibrated by a two-particle generator with spray and soot type methods applied on the nano-sized particle distribution’s parameters such as number concentration and linearity. Also, in order to ensure the reliability for particle sensor system named as PPS, which had emerged as a useful diagnostic to making spatially and temporally resolved quantitative measurements of diesel PN concentration, it was compared with calibrated CPC system. As a result, nano-sized particle measuring system with CPC calibrated by spray type particle generator had a much higher counting efficiency, indicating a larger nano size available than soot type particle generator. And, comparative experimental results on the correlation between the particle number of CPC to a reflectance PPS system showed that above 5,000 #/cm3 in number concentrations measured by CPC as well as PPS were found to be similar with good linear relationship.