The effects of humidity on volume recombination in ionization chambers

Takata, N.

doi:10.1088/0031-9155/39/6/010

Cited by 8 publications

(5 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recombination in columns takes place after ions have drifted a distance larger than hr. A similar effect of humidity has been observed for m, which is a parameter for volume recombination-the value of m increases sharply in a range of short ion lifetimes and increases more slowly at longer lifetimes (Takata 1994). Dotted lines in figure 4 show the change in the value of for each applied voltage as in figure 2, except that the dotted lines are corrected for back-diffusion loss.…”

Section: P(z)supporting

confidence: 65%

“…The experimental values of E1 shown in figure 3 have been obtained by neglecting the loss of ions due to volume recombination. If we assume that m = 19 x lo6 V A-' m-llz, which is the largest value obtained for air with humidity of 81% (Takata 1994). the volume recombination loss becomes 3.8 x for data measured at U = 0.5 V, 1/E = 14 mm V-' (i.e.…”

Section: Discussionmentioning

confidence: 90%

See 1 more Smart Citation

Ion loss due to initial recombination in a parallel-plate cavity ionization chamber

Takata¹

1994

Phys. Med. Biol.

Self Cite

View full text Add to dashboard Cite

Collection efficiencies for ion loss due to initial recombination and back-diffusion were measured for several humidities using a parallel-plate cavity ionization chamber irradiated with 60Co gamma-rays. It was shown, from measurements in a range of inverse electric field strengths from 0.05 to 14 mm V(-1), that initial recombination took place both in clusters and columns of ions produced along the path of the secondary electrons ejected by the y-rays. The ion loss due to recombination in clusters was found to increase with humidity, but that in columns did not. Effects of ion clustering reactions on recombination may be reduced after longer periods of ion drift, when recombination in columns takes place. Ion loss due to back-diffusion was also found to have no dependence on humidity.

show abstract

Section: P(z)supporting

confidence: 65%

Section: Discussionmentioning

confidence: 90%

Ion loss due to initial recombination in a parallel-plate cavity ionization chamber

Takata¹

1994

Phys. Med. Biol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…This suggests that the effect of humidity is similar for each type of recombination, at least in the limits of the present uncertainties. The results do not contradict those of Takata (1994), for which the measuring conditions and the range of H values used were very different. 4).…”

Section: Humiditycontrasting

confidence: 46%

“…Seeman (1912) 1 3.88 Boag and Wilson (1952) 3.76 Shevyrev (1960) 3.69 Tate and East (1961) 4.24 Ritz and Attix (1962) 4.75 Kemp and Barber (1963) 4.62 Niatel (1967) 3.33-4.09 Böhm (1976) 3.03 Moriuchi et al (1978) 4.04 Boag (1987) 4.04 Heese et al (1985) 3.24 2 Takata (1994) 3.06…”

Section: Authors Mmentioning

confidence: 99%

Volume recombination parameter in ionization chambers

Boutillon

1998

Phys. Med. Biol.

View full text Add to dashboard Cite

The parameter m2 governing the volume recombination in ionization chambers has been measured under conditions which allow strict application of the basic theory. The method consists of measuring the ratio of ionization currents I(V1) and I(V2) obtained at two given voltages V1 and V2 as a function of I(V1). The value of m2 is derived from a linear extrapolation to zero current. Several pairs of voltages (V1, V2) were used. The value of m2 obtained in this work is 3.97 x 10(14) s m(-1) C(-1) V(2) with a relative uncertainty of 1.7%. The dependence of m2 on atmospheric conditions has also been investigated.

show abstract

“…Away from the ideal saturation current in an ionization chamber (I s ), real output current (I) is usually lower due to incomplete charge collection as a result of several effects, being: Initial recombination, Back-diffusion to electrodes, and Volume recombination [ 12 ]. The collection efficiency for an ion chamber ( f ) can be evaluated according to the following relation:…”

Section: Methodsmentioning

confidence: 99%

Efficiencies of Some Spherical Ion Chambers in Continuous and Pulsed Radiation: A Numerical Evaluation

Maghraby

2015

Pol J Radiol

View full text Add to dashboard Cite

SummaryBackgroundEvaluation of the collection efficiencies of ion chambers is a necessity for the proper evaluation of radiation quantities in different applications. Overall collection efficiency is the product of three different values: collection efficiencies considering contributions of, volume recombination, back-diffusion loss and initial recombination, the later may be neglected at low charge rates.Material/MethodsFive common spherical ion chambers of different volumes and specifications were included in this study for the evaluation of volume recombination collection efficiency and back diffusion collection efficiency for continuous and pulsed radiation and at different values of the applied polarizing potential. Through current work there is an attempt of focusing on how the selection of ion chamber dimensions may affect the overall collection efficiency in addition to the proper selection of other influencing parameters.ResultsCollection efficiencies considering volume recombination (fv) for five spherical ion chambers of common types were evaluated for continuous and pulsed radiation over a wide range of polarizing potential. The relation between the ion chamber volume and its evaluated collection efficiencies were studied for both continuous and pulsed radiation; transit time values for the ion chambers included in this study were evaluated at different values of applied potential. Also, collection efficiencies considering diffusion current values (fd) were evaluated for the five chambers, and plotted versus the applied polarizing potential.ConclusionsThrough this study it was feasible to evaluate numerically the collection efficiencies of some spherical ion chambers considering volume recombination and back diffusion effects; the affecting parameters were studied and highlighted.

show abstract

The effects of humidity on volume recombination in ionization chambers

Cited by 8 publications

References 7 publications

Ion loss due to initial recombination in a parallel-plate cavity ionization chamber

Ion loss due to initial recombination in a parallel-plate cavity ionization chamber

Volume recombination parameter in ionization chambers

Efficiencies of Some Spherical Ion Chambers in Continuous and Pulsed Radiation: A Numerical Evaluation

Contact Info

Product

Resources

About