A new type of neutron detector, which consists of polyethylene. They generally provided technical comments that we included as appropriate. Instruction focuses on handson measurements in a laboratory setting using real nuclear material in small groups led by experienced instructors. The most common neutron detectors are of the proportional gas type. Requirements on neutron detectors alternative to he3. Neutron coincidence counting one of the more common applications of neutron detection and counting is the assay of fissile materials via the sf signature of the fertile nuclides. University of california lawrence radiation laboratory, 1962 neutron counters 38 pages. Acquisition of neutron detector spectra of the type of bf3, he3 and b10 using the winspect system in the argonauta reactor of iencnenrj dante l. The gamma ray ccl neutron tool utilizes a scintillation style detector using a 1inch diameter x 4inch long crystal for the gamma ray measurement. There is a wide field of applications for he3 proportional counters, such as monitoring of natural neutron radiation, homeland security.
In addition, these systems are required to meet all aspects of the ansi n42. Old studsvik 2202d neutron monitors can be upgraded to 2222a see pdf 2202d to 2222a upgrade kwd pdf sheets. Other than protium ordinary hydrogen, helium3 is the only stable isotope of any element with more protons than neutrons. General 6 slow neutron detectors are far more common. Helium3 proportional counters and alternatives for neutron. When the fissile material is contained in a high density.
Identification of special nuclear material by neutron detection. Lnd nuclear radiation detectors products neutron detectors he3 detectors cylindrical he3 neutron detectors 25183. A typical bf 3 detector consists of a cylindrical aluminum brass or copper tube filled with a bf 3 fill gas at a pressure of 0. The existing device, the superfluid he3 cell, will be briefly introduced. Neutron detection gamma ray sensitivity criteria sciencedirect. Training courses focus on nondestructive assay techniques applied to nuclear safeguards and security applications. As in photon detection, the interaction cross section must be as large as possible to achieve a high efficiency.
It is well known that there are three ways to improve neutron scattering. Enhanced formation evaluation our helium3 he3 filled detectors offer the optimal combination of high efficiency and sensitivity, with good gamma discrimination and excellent vibration. We provided a draft of this report to commerce, dod, doe, and dhs. Neutron detection neutrons have mass but no electrical charge. The anode signal from the detector was directly readout by a caen dt5720 digitizer 12 bit, 2 v dynamic range, 4. Comparative neutron detection efficiency in he3 proportional. Itcan be seen thatthe prototype detector is comparable to a he3 tube surrounded by 16mmofhdpe, and is roughly the same size and weight. Most neutron area detectors use 3he as the detection gas that undergoes the following. Underground neutron detection through nuclear recoil.
Evidence of fast neutron sensitivity for 3he detectors and. Theory of detection helium3 proportional counters utilize the hea n,p 1 reaction for the detection of thermal neutrons. Popular nuclear reactions slow neutrons are in the energy range below 0. There are three basic requirements for neutron detectors for safeguards applications involving detection and measurement of snm. This is considerably less than the cross section of he3 for thermal neutrons. Compared to he3, bid has a lower cross section for. The shortage of 3 he has triggered the search for effective alternative neutron detection technologies for national security and safeguards applications.
The energy resolution of a helium3 detector is strictly related to the discrimina. Neutron capture same as non elastic scatter, but by definition, neutron capture occurs only at low neutron energies thermal energy range is neutron detection neutrons have mass but no electrical charge. The active detection area of typical neutron area detectors is 64 cm64 cm with a spatial resolution of either 1 cm1 cm for the cerca detector or 0. The neutron detector with corona tube has a scheme of functionally quite similar to that of a normal geiger tube, given that both work in the discharge region. Our helium3 he3 filled detectors offer the optimal combination of high efficiency and sensitivity, with good gamma discrimination and excellent vibration response, all in the most compact package possible. Modelling detector responses to neutrons using mcnp. Comparison of neutron detection efficiency of a he3 counter and a boron10 loaded liquid scintillator. The cf252 sourceisshielded and the detector was without a moderator. The detector efficiency is high around 75 % for typical neutron wavelengths around. He3 measurements with lowradioactivity background fast neutron. A response matrix is constructed which can be used to convert an energy dependent neutron flux into a pulseheight spectrum for a particular detector configuration. Any new detection technology must satisfy two basic criteria. Pdf twochannel highpressure helium3 scintillation neutron. Since neutrons themselves have no charge and are nonionizing, they are not so easy to detect as xrays.
He3 neutron detectors bf3 neutron detectors contain boron enriched to bio the thermal neutron cross section for bio is 3840 barns. We developed a technique for thermal neutron detection not making use of 3he, also suitable for online real time monitoring of castor spent fuel containers. Removable gamma detector allows close inspection of samples with included 5ft extension cable and can be combined with a low background shield for low radioactivity levels in samples such as food, soil or water. The neutron detector shall not generate alarms due to the presence of strong gammaray sources. Riideye xm series handheld radiation isotope identifiers. Helium3 3 he, tralphium, see also helion is a light, stable isotope of helium with two protons and one neutron common helium4 having two protons and two neutrons. The front surface area of this detector was 127 cm 2. Fast neutron sensitivity for 3 he detectors and comparison with. Pdf a superfluid he3 detector for direct dark matter.
Helium3free lowcost neutron detectors epj web of conferences. The 3he based neutron detectors are no longer the default solution for. Detection hardware refers to the kind of neutron detector used the most common today is the scintillation detector and to the electronics used in the detection setup. More than 100,000 detectors now in service around the world support a broad range of instrumentation needs, from reactor monitoring and security applications to neutron research and oil exploration. Zns and lif based neutron detectors saintgobain crystals. Department of energy august 2012 neutron detectorelectronics biggest bang for the buck. Novel neutron detector makes scintillating debut nist. Low signals and backgrounds motivate large imaging detectors. Detection hardware refers to the kind of neutron detector used the most common today is the scintillation detector and to the. The energy information obtained in neutron detection systems is usually poor. Special nuclear material snm such as plutonium239, uranium233, or uranium235 is used in the creation of nuclear explosives and atomic bombs due to its fissile nature, or capability to selfsustain a chain reaction with neutrons.
Then, a capture reaction such as 3 hen,p 3 h, 6 lin. He 3 neutron detectors provide an output pulse which. Lnd nuclear radiation detectors products neutron detectors he3 detectors cylindrical he3 neutron detectors 2523. The model 124 is an industry standard neutron dose rate instrument that conforms to the rpg curve with a measuring range of 0 to 100 svh 0 to 10,000 mremhr from thermal to 12 mev. The neutron dose rate can be measured over a broad range, from 0. Safeguards and security technology training program. Gasbased thermal neutron detectors stanford university. When an incoming neutron hits a boron atom, the atom splits into pieces which travel into the xenon gas, exciting the atoms there. Apr 25, 2016 aspect is available to assist local, national, and international agencies supporting hazardous substance response, radiological incidents, and situational awareness in the us. For the first time, the sensitivity of 3he detectors to fast neutrons, up to. Count rates of order 5104 counts per second over the.
Compared to he3, bid has a lower cross section for thermal neutrons, making bf3 detectors less sensitive. A compactneutrondetectorbasedonthe use ofa sipm detector. As in photon detection, the interaction cross section must be as large as. Gamma ray ccl neutron tool probe cased hole logging. In a thermal neutron detector, a neutron is slowed down to thermal energies in a moderator that typically surrounds the detector. Pdf comparison of neutron detection efficiency of a he3. Aspect is available 247365 and can be collecting data at any site in the continental us within nine hours. The instrument contains a single 1inch diameter x 6inch long he3 neutron detector.
He3 tube electronics preamp maps detector adc vme board charge division used for position determination. The 3hebased neutron detectors are no longer the default solution for. There are common requirements for slow neutron detection. There are two key aspects to effective neutron detection. Detector response and neutron energy unmodified neutron detectors e. The crystal is coupled to a ruggedized high temperature photomultiplier tube packaged in a shockmounted assembly. Department of energy under contract deac0576rl01830 pnnl19110 3he neutron detector pressure effect and comparison to. He3 built to operate in extreme environments such as high or low temperatures, high pressures and high shock and vibration. New neutron detector based on micromegas technology for ads projects. Moderated clyc neutron detector uses no he3 and is located in electronics case to maximize space. Response functions for each of these reactions are then calculated, taking into account the production of multiple gammarays in a single neutron interaction. This means that neutron detectors must rely upon a conversion process where an incident neutron interacts with a nucleus to produce a secondary charged particle. The 2222a is a complete monitor comprising a neutron detector and an electronic unit. Multiple modules can be easily interconnected providing a single digital counting channel that will process pulse rates exceeding 5 mhz.
Lnd nuclear radiation detectors products neutron detectors he3 detectors cylindrical he3 neutron detectors 2517. The currently deployed radiation portal monitors rpms from ludlum and science applications international corporation saic use neutron detectors based upon 3hefilled gas proportional counters, which are the most common large neutron detector. Characterisation of the spatial resolution and the gammaray. Bf3 commonly used as neutron gas detector prior to the widespread availability of he3. This type of detector is very insensitive to photon radiation, and the remaining amount may be well discriminated by electronic means. Gamma and neutron irradiation of iaea employed he3 counters and electronic determination of relative and absolute efficiency as function of threshold setting no gamma interference up to a dose rate of 1. The ratio of neutron sensor gammaray detection efficiency to neutron detection shall be less than 0. Neuport neutruck is a 6 lifznsag based neutron detector to replace he3 tube in radiation portal and mobile monitors. The idea is to use superfluid he3 as a sensitive medium. Because of this they cannot directly produce ionization in a detector, and therefore cannot be directly detected.
C it undergoes an n alpha interaction with thermal neutrons. Neutron monitor 2222a he3 kwd nuclear instruments ab. Helium3 and bf3 detectors find many applications in passive and aotive. Mache3 matrix of cells of superfluid he3 is a project of a new detector for direct dark matter search.
The dual magnet center coil ccl provides maximum sensitivity through 7inch diameter casing. Pdf alternatives to 3he for neutron detection for homeland. The method of detection relies on the absorption of the neutron by an atom with the simultaneous emission of a. A slow neutron detector can be modified so that it responds to both slow and fast neutrons. Helium3 neutron detectors are largely sensitive to thermal neutrons and are typically used with a neutron moderator.
Pdf a superfluid he3 detector for direct dark matter search. The charge sensitive amplifiers are designed for helium3, boron loaded, fission chamber, alphaand protonrecoil neutron detector operation. Pdf we have developed a twochannel, highpressure 3he gas scintillation detector that operates in coincidence mode. Neutron detection is an essential aspect of interdiction of radiological threats for national security purposes, since plutonium, a material used for nuclear weapons, is a significant source of. The energy of the reaction is carried away as kinetic energy of the daughter products, which move in opposite directions. No other company understands your radiation measurement requirements better than our people at reuterstokes. Gasbased thermal neutron detectors veljko radeka for the bnl neutron detector team.
Neutron detection is the effective detection of neutrons entering a wellpositioned detector. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. Proprietary pulse shape discrimination psd algorithm is employed to count neutrons and reject gamma ray events. A cf252 neutron and co60 gammaray spectra taken with a sciontx 16p3 i 10lie2tx2, the sameasused byg.