Advances in Superheated Drop (Bubble) Detector Techniques

D’Errico, Francesco; Alberts, W.G.; Matzke, M.

doi:10.1093/oxfordjournals.rpd.a031921

Cited by 28 publications

(7 citation statements)

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“…Passive pen-detectors have been developed with optical or volumetric registration of the bubbles, as well as active counters detecting bubble nucleations acoustically. 3,4 A variety of halocarbons are employed in the formulation of the detectors, and this permits a wide range of applications. In particular, halocarbons with a moderate degree of superheat, i.e., a relatively small difference between their operating temperature and boiling point, can be used in neutron dosimetry and spectrometry since they are only nucleated by energetic heavy ions such as those produced by fast neutrons.…”

Section: Introductionmentioning

confidence: 99%

A model for photon detection and dosimetry with superheated emulsions

2000

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A model is presented for the analysis and prediction of the photon response of detectors based on superheated emulsions of light halocarbons in tissue equivalent gels. It is shown that on the basis of a nondimensional thermodynamic quantity, called reduced superheat, it is possible to identify the degree of superheat, or the operating temperature, corresponding to the photon sensitization of the emulsions. Moreover, on the basis of the mass energy absorption coefficients, it is possible to determine the energy dependence of the photon response. The vaporization energy necessary for bubble nucleation is estimated by means of the thermal spike theory developed for bubble chambers. The energy deposition requirements are consistent with the energy transferred by secondary electrons at the end of their range in the halocarbons. These findings provide design criteria for photon detectors based on superheated emulsions. It is shown that light halocarbons of low effective atomic numbers present the best dosimetric properties. In particular, by manufacturing superheated emulsions with octafluoropropane, or halocarbon R-218, photon sensitivity is achieved at room temperature along with a fairly constant air-kerma response.

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Section: Introductionmentioning

confidence: 99%

A model for photon detection and dosimetry with superheated emulsions

2000

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“…Several devices based on this technology have been designed. 7 Some are active counters acoustically detecting the sound pulses emitted when drops vaporize. Recent versions perform pulse shape analysis, record the exposure time-history and provide dose rate estimates.…”

Section: Introductionmentioning

confidence: 99%

In‐phantom dosimetry and spectrometry of photoneutrons from an 18 MV linear accelerator

D’Errico¹,

Nath²,

Tana³

et al. 1998

Medical Physics

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A combination of three superheated drop detectors with different neutron energy responses was developed to evaluate dose-equivalent and energy distributions of photoneutrons in a phantom irradiated by radiotherapy high-energy x-ray beams. One of the three detectors measures the total neutron dose equivalent and the other two measure the contributions from fast neutrons above 1 and 5.5 MeV, respectively. In order to test the new method, the neutron field produced by the 10 cm X 10 cm x-ray beam of an 18 MV radiotherapy accelerator was studied. Measurements were performed inside a tissue-equivalent liquid phantom, at depths of 1, 5, 10 and 15 cm and at lateral distances of 0, 10, and 20 cm from the central axis. These data were used to calculate the average integral dose to the radiotherapy patient from direct neutrons as well as from neutrons transmitted through the accelerator head. The characteristics of the dosimeters were confirmed by results in excellent agreement with those of prior studies. Track etch detectors were also used and provided an independent verification of the validity of this new technique. Within the primary beam, we measured a neutron entrance dose equivalent of 4.5 mSv per Gy of photons. It was observed that fast neutrons above 1 MeV deliver most of the total neutron dose along the beam axis. Their relative contribution increases with depth, from about 60% at the entrance to over 90% at a depth of 10 cm. Thus, the average energy increases with depth in the phantom as neutron spectra harden.

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“…Bubble detectors [16][17][18] are suspensions of over-expanded halocarbon and/or hydrocarbon droplets (about 100 µmin diameter) which vaporise upon exposure to the high LET recoils from neutron interactions. The superheated droplets are dispersed in a gel-like medium contained in a vial and act as continuously sensitive, miniature, bubble chambers.…”

Section: Instrumentationmentioning

confidence: 99%

Radiation produced by the LEP superconducting RF cavities

Silari

Agosteo

Gaborit

et al. 1999

Nuclear Instruments and Methods in Physics Research Section A:

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The LEP superconducting RF cavities present an important radiation source both during the conditioning and during normal working conditions. Before their installation in the accelerator the cavities are tested and conditioned in a laboratory bunker up to their maximum achievable field, which in some cases can be as high as 9 MV m-1 . This paper discusses radiation measurements carried out on both single cavities and standard 4-cavity modules. Following a brief description of the processes underlying the emission of radiation, the results of photon and neutron measurements are given. The induced radioactivity in various materials is also evaluated; shielding guidelines and radiation protection procedures are briefly discussed.

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Advances in Superheated Drop (Bubble) Detector Techniques

Cited by 28 publications

References 0 publications

A model for photon detection and dosimetry with superheated emulsions

A model for photon detection and dosimetry with superheated emulsions

In‐phantom dosimetry and spectrometry of photoneutrons from an 18 MV linear accelerator

Radiation produced by the LEP superconducting RF cavities

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