MeV Alpha Particles Research Articles

A DLTS analysis of alpha particle irradiated commercial 4H-SiC Schottky barrier diodes

4H-SiC Schottky barrier diodes (SBDs) were exposed to 5.4 MeV alpha particles with fluences of 2.55× 1011 cm−2, 5.11 × 1011 cm−2 and 7.67 × 1011 cm−2, respectively. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) was used to determine the structure and cross-sectional elemental composition of the device, while current–voltage and capacitance–voltage profiling were used to determine the primary electrical device-characteristics before and after irradiation. EDS revealed the presence of a <1 μm Ti layer, covered by 5 μm Al layer, in intimate contact with the SiC. Deep level transient spectroscopy (DLTS), performed in the temperature range 15–310 K, revealed one dominant peak around 50 K (Ec - 0.07 eV) in the unirradiated samples. This peak showed asymmetry suggesting that it may consist of more than one defect. Notably, Z1/2, the carbon vacancy-related (Vc) defect commonly observed in as-grown n-type 4H-SiC, was not detected in the unirradiated reference sample. After irradiation, a broad peak emerged around 280 K (at 80 Hz), most likely Z1/2, having a shoulder around 180 K, was detected. Increasing the fluence resulted in a corresponding decrease in the concentration of the electron trap observed around 50 K (Ec - 0.07 eV), while the concentration increases for the defect detected around 280 K. Notably, the concentration of Z1/2 was found to be strongly fluence dependent and linked to what we believe is a related to a silicon vacancy transition, labelled S1/2 in literature. Laplace DLTS confirmed that the peak observed around 50 K is composed of multiple defects.

Single Event Effects in 3.3 kV 4H-SiC MOSFETs due to MeV Ion Impact

In this work, MeV alpha particles generated from an accelerator are used to study single event breakdown (SEB) in 4H-SiC MOSFET samples, rated at 3.3 kV. The samples are exposed to bursts of alpha particles under reverse bias conditions to investigate the SEB sensitivity to ion energy and reverse bias. The energies of alpha particles are chosen to reach different depths in the drift region of the MOSFET devices, and also to penetrate the whole drift region. Forward and reverse characteristics are measured after each exposure, as long as no failures occur, to ensure that the device performance is maintained. The measurements show that no significant effects are observed on the drain-source leakage current, while minor effects on gate behavior can be seen as a function of accumulated fluence. Furthermore, SEB can only be triggered with a reverse bias larger than, or equal to 3 kV. A standard MOSFET cell with a similar rated voltage is also simulated in Sentaurus TCAD to study these effects, using two different models for the incident ion-induced ionization: the Alpha Particle and the Heavy Ion model. Simulations show that the Alpha Particle model cannot induce any device failures even with a 3.5 kV reverse bias, while it is possible to trigger a failure by the Heavy Ion model, where the ionization can be selected. Carrier plasma and internal electric field distributions of the two models are plotted and compared, showing that device failures triggered by a heavy ion are related to the hole injection at epi-substrate interface, in which linear energy transfer (LET) of the particle plays an important role.

Development of an ultrahigh resolution 1 mm Si-PM array based GGAG alpha particle imaging detector with gamma or X-ray separation capability

For precise distribution measurements of alpha particles, as required in alpha radionuclide therapy research, a high-resolution alpha particle imaging detector is desirable. While combining a thin scintillator with a photodetector array, such as a position-sensitive photomultiplier (PSPMT), is a potential method to develop an event-by-event-based alpha particle imaging detector, the spatial resolution is currently limited to around 0.8 mm FWHM. To overcome this limitation, we utilized a small-sized Si-PM array combined with a thin GGAG plate to create an alpha particle imaging detector and evaluated its performance. In the developed alpha particle imaging detector, a Si-PM array with a channel size of 1 mm × 1 mm arranged in an 8 × 8 configuration was optically coupled to a 1 mm thick GGAG plate, with a 1-mm-thick light guide between them. Since the decay times of GGAG differ between alpha particles and gamma photons or X-rays, we were able to separately measure the distributions of alpha particles and gamma photons using pulse shape discrimination. The spatial resolution of the developed alpha particle imaging detector was 0.19 mm FWHM, and the energy resolution was 11% FWHM for 5.5 MeV alpha particles. Additionally, we were able to separately measure the distributions of alpha particles and gamma photons for simultaneously irradiated phantoms using pulse shape discrimination. The developed imaging detector shows promise for distribution measurements of alpha particles, as well as gamma photons or X-rays, where high spatial resolution and separation of gamma photons or X-rays are required.

Measurement of Naturally-Occurring Radioactive Materials (NORM) using a scintillator-based alpha detector

It is important to differentiate between natural and artificial radioactive materials such as plutonium in nuclear facilities. In this study, a scintillator-based alpha-particle detector was developed using YAP:Ce scintillator and Multi-Anode PhotoMultiplier Tube. The detector was used to measure various naturally occurring radioactive materials (NORM) samples including radon progeny, lead plate, lantern mantle, and radium ceramic ball. The measurement results were compared with Monte Carlo simulation calculations and were found to be in agreement. The energy resolution of the detector is 8.6%FWHM. In the measurement results of radon progeny, peaks of 212Bi (6.1 MeV), 214Po (7.7 MeV), and 212Po (8.8 MeV) can be observed. The lead plate contains 210Po and emits 5.3 MeV alpha particle. The simulation with the same energy was able to reproduce the actual measurement. The results showed the energy and distribution of the alpha particles emitted by the NORM samples. The study successfully demonstrated the capability of the developed alpha-particle detector in identifying NORM.

Low energy alpha particles dose mapping with a combination of CR-39 detector and a high resolution flatbed scanner

The potential of a combination of the well-known CR-39 detector and a high-resolution flatbed scanner for low energy alpha particles dose mapping is investigated. The CR-39 detectors were irradiated with perpendicular incident 4 MeV alpha particles of doses 0.009, 0.018, 0.033, 0.051, 0.067, 0.134, and 0.164 Gy, thereafter, etched in 6.25 N NaOH at 70 °C. The CR-39 detectors were scanned with Canon CanScan 9000F Mark II of spatial resolution of 9600 dpi and color depth of 48 bit. The measurements reveal that the pixel values for different color channels are correlated linearly with 4 MeV alpha particles dose at the etching times of 2 h, 3 h, and 4 h. For blue channel, the maximum sensitivity was −53178 ± 1463 pixel value/Gy at etching time of 4 h, compared to −15290 ± 2004 pixel value/Gy, and −42255 ± 840 pixel value/Gy at 2 h and 3 h respectively, the negative sign indicates the pixel values decrease as the 4 MeV alpha particles dose increases. While for etching times, 5 h and 6 h, the pixel values decrease exponentially as the 4 MeV alpha particles dose increases. For prolonged etching time, the pixel values are non-monotonic function of alpha particles dose. The optical density was evaluated as a function of etching time (removal thickness) of CR-39 irradiated with different doses. For 0.009 Gy, and 0.018 Gy doses of alpha particles, the optical density is linearly correlated with the etching time; for other doses, the optical density is not a monotonic function of the etching time. These new findings pave the way to use the combination of the CR-39 detector and high-resolution flatbed scanner for dose mapping of alpha particles and heavy ions over large-scale areas, applying etching conditions for each particle type and corresponding energy, that produce maximum sensitivity and linearity.

Preliminary Characterization of an Active CMOS Pad Detector for Tracking and Dosimetry in HDR Brachytherapy.

We assessed the accuracy of a prototype radiation detector with a built in CMOS amplifier for use in dosimetry for high dose rate brachytherapy. The detectors were fabricated on two substrates of epitaxial high resistivity silicon. The radiation detection performance of prototypes has been tested by ion beam induced charge (IBIC) microscopy using a 5.5 MeV alpha particle microbeam. We also carried out the HDR Ir-192 radiation source tracking at different depths and angular dose dependence in a water equivalent phantom. The detectors show sensitivities spanning from (5.8 ± 0.021) × 10-8 to (3.6 ± 0.14) × 10-8 nC Gy-1 mCi-1 mm-2. The depth variation of the dose is within 5% with that calculated by TG-43. Higher discrepancies are recorded for 2 mm and 7 mm depths due to the scattering of secondary particles and the perturbation of the radiation field induced in the ceramic/golden package. Dwell positions and dwell time are reconstructed within ±1 mm and 20 ms, respectively. The prototype detectors provide an unprecedented sensitivity thanks to its monolithic amplification stage. Future investigation of this technology will include the optimisation of the packaging technique.

Li–Pd–Rh-D2O electrochemistry experiments at elevated voltage

In 2013, the U.S. Navy disclosed an electrochemistry procedure intended to produce MeV-energy nuclear particles, based on eV-energy electrical inputs, which may be indicative of a new scientific phenomenon. This work is based on the 2013 disclosure and shows initial evidence validating the prior claims of nuclear particle generation. Additionally, several variations on the 2013 electrochemical recipe are made in order to find a highly repeatable recipe for future replications by other teams. The experiments described here produced dense collections of tracks in solid-state nuclear track detectors, radio frequency (RF) emissions, and anomalous heat flux, which are indicative of potential nuclear, or unusual chemical, reactions. Experimental results include tracks in solid-state nuclear track detectors similar in size to tracks produced by 4.7 MeV alpha particles on identical detectors exposed to radioactive Th-230; RF pulses up to 6 dB above the noise floor, which indicate that these signals were likely not background noise and not caused by known chemical reactions; and heat flux of 10 s of kJ, measured to 6σ significance, over and above input electrical energy, indicative of unknown exothermic reactions. Six out of six nuclear track detectors, utilized in experiments and interrogated for tracks post-experiment, produced positive results that our team attributes to thousands of individual particle impacts in dense clusters, likely with energies between 0.1 and 20 MeV. Similar nuclear particle, thermal, and RF results have separately appeared in prior reports, but in this work, all three categories of anomalous behavior are reported. Results indicate that the 2013 procedure may be a useful guide toward a set of highly repeatable reference experiments, showing initial but not overwhelming evidence of a new scientific phenomenon. Repeatable recipes are shared so that other groups may replicate and extend the present work.

Optical features and radiation absorption efficiency of borate glasses and the role of PbO/ Eu2O3 substitution

In the present research, the optical parameters and those related to the interactions of charged radiation and neutrons of 50B2O3 – 15Na2O – 15ZnO – (20-x)PbO-xEu2O3 (for x = 0, 2, and 3 mol%) glass system were investigated. The roles of Eu2O3 content on the evolution of the physical, optical, and shielding abilities of the glasses were presented. The glasses were prepared using the conventional melting-and-quenching method and coded as BNZPE1, BNZPE2, and BNZPE3 for Eu2O3x = 0, 2, and 3 mol%, respectively. To characterize the prepared glasses for radiation applications, two glasses of particulate radiation were considered: charged radiation and uncharged radiation.The densities of BNZPE1, BNZPE2, and BNZPE3 are 3.99 g/cm3, 4.02 g/cm3, and 4.27 g/cm3, respectively. The values of Eg are 3.04 eV, 3.28 eV, and 3.58 eV for BNZPE1, BNZPE2, and BNZPE3, respectively. Both Rm and αm followed a downward trend as Eu2O3 content rose. The static and optical dielectric constants decrease from 5.688 to 5.090 and 4.688 to 4.090, respectively, as the Eu2O3 content rises. The projected range of 15 MeV electrons, protons, alpha particles, and carbon ions was 20341 μm, 1010 μm, 96 μm, and 10.48 μm for BNZPE1, 20206 μm, 998.21 μm, 95 μm, and 10.42 μm for BNZPE2, and 19053 μm, 939.59 μm, 90 μm, and 9.82 μm for BNZPE3. The removal probabilities of FN in BNZPE1, BNZPE2, and BNZPE3 are 0.1086, 0.1089, and 0.1154 cm−1, respectively. The FN shielding abilities of the BNZPE-glasses are better than those of different categories of concrete and some known glass shields The glass with the highest Eu2O3 content has the highest charged particle FN, and TN interaction probabilities.

Activation cross section measurement of alpha-particle induced nuclear reactions on tantalum

Activation cross sections induced by 50 MeV alpha-particle beam on natural tantalum were measured at the AVF cyclotron of the Nishina Center of RIKEN. The well-established stacked target technique and activation method were applied followed by high-resolution gamma spectrometry to determine the reaction cross sections. The experiment aimed to determine activation cross sections for the longer-lived reaction product. Accordingly, activation cross sections were deduced for the formation of 181, 182m, 182g, 183, 184m, 184gRe and 178g, 182gTa.

Secondary scintillation properties of multi-layer THGEMs operated in low-pressure CF4 and Ar/5%Xe

We present a measurement of the secondary scintillation yield produced by two-layer Thick Gas Electron Multipliers (M-THGEMs) in pure Tetrafluoromethane (CF4) gas and in Ar mixed with 5% Xe in low-pressures down to 20 Torr. The detector was irradiated with 5.49 MeV alpha particles from a low-rate 241-Am source. The secondary scintillation light generated during the gas avalanche process was read out by a Hamamatsu photomultiplier tube (model R8520-406), sensitive to a broad wavelength range (160–650 nm). The avalanche charge was collected on the bottom electrode of M-THGEM and correlated to the scintillation light on an event-by-event basis. We observed that, for both gas types, the value of the photon to electron production ratio (0.4 ph/el in CF4 and 0.1 ph/el in Ar/5%Xe) increases with the thickness of the M-THGEM electrodes and varies significantly with the pressure, being higher at lower values. The decrease in electroluminescence yield at higher pressures is much more pronounced in the Ar/Xe mixture. In addition, because of a larger gas avalanche volume, the electroluminescence light yield is larger in thicker M-THGEM structures. Presented results are particularly useful for designing the next generation of Optical-readout Time Projection Chambers (O-TPCs) operated at low-pressure CF4; applications include experimental nuclear physics with rare isotope beams, dark matter detection with directional sensitivity and observation of the Migdal effect in a low-pressure Optical TPC.

Development of Directional 14 MeV-Fusion Neutron Detector Using Liquid-Scintillator-Filled Capillaries

Triton burnup studies have been performed in fusion experimental devices to evaluate the confinement performance of 3.5 MeV alpha particles. For this purpose, the generation rate of deuterium-tritium (D-T)-born 14 MeV neutrons has been measured using a scintillating fiber detector. The directionality of this detector provides excellent selectivity for 14 MeV neutrons; however, the lack of a pulse–shape discrimination (PSD) capability limits high-energy gamma-ray reduction. In this study, we developed a new 14 MeV neutron detector with directionality that can discriminate neutrons and gamma rays based on the PSD technique by filling capillaries with a liquid scintillator. The performance of this detector was evaluated at the FNL (Tohoku University, Japan) and OKTAVIAN (Osaka University, Japan). The detector response was modeled using the particle and heavy ion transport code system (PHITS). The experimental and simulation results demonstrated that the detector has a directional response to fast neutrons and excellent PSD capability.

Separation of 71,72As from alpha-particle induced reaction on gallium oxide target using naturally occurring alkaloid caffeine

Abstract Gallium oxide target was irradiated with 46 MeV alpha-particle beam, which produced 71,72As and 67Ga radioisotopes in the matrix. Separation of radio-arsenics from the bulk gallium target was carried out by caffeine, a nature-resourced reagent, extracted from black tea leaves. 71,72As radionuclides were preferentially attached with caffeine and precipitated with caffeine in 2 M Na2SO4 solution as caffeine was insoluble in aqueous medium under this condition. With increase in weight of caffeine, extraction of 71,72As and bulk gallium significantly increased. Bulk Ga along with 67Ga remained in the supernatant. Geometry optimization of caffeine–metal complex was carried out by theoretical computational analysis. DFT calculation corroborated with the experimental findings where As3+ preferentially binds with caffeine in presence of gallium and arsenic. As evidenced by the short As–O and As–N distances, the high binding energies are a result of the metal ion’s strong binding to the carbonyl and nitrogen centres, whereas no such result could be obtained in case of bulk gallium.

First measurements of p11B fusion in a magnetically confined plasma

Proton-boron (p11B) fusion is an attractive potential energy source but technically challenging to implement. Developing techniques to realize its potential requires first developing the experimental capability to produce p11B fusion in the magnetically-confined, thermonuclear plasma environment. Here we report clear experimental measurements supported by simulation of p11B fusion with high-energy neutral beams and boron powder injection in a high-temperature fusion plasma (the Large Helical Device) that have resulted in diagnostically significant levels of alpha particle emission. The injection of boron powder into the plasma edge results in boron accumulation in the core. Three 2 MW, 160 kV hydrogen neutral beam injectors create a large population of well-confined, high -energy protons to react with the boron plasma. The fusion products, MeV alpha particles, are measured with a custom designed particle detector which gives a fusion rate in very good relative agreement with calculations of the global rate. This is the first such realization of p11B fusion in a magnetically confined plasma.

Fusion product diagnostics based on commercially available chemical vapor deposition diamond detector in large helical device

Fusion product diagnostics based on four commercially available single-crystal chemical vapor deposition (s-CVD) diamond detectors are installed in the Large Helical Device (LHD) in order to understand energetic ion confinement. Characteristics of s-CVD diamonds were surveyed using alpha and D-T neutron sources. It is found that the energy resolutions of s-CVD diamonds for ∼ 5 MeV alpha particles and 14 MeV neutrons are 1%–3% and ∼ 1.7%, respectively. Moreover, the response of four s-CVD diamond detectors to alpha particles and D-T neutrons is almost identical. The installation positions of the diamond detectors in the vacuum vessel are searched for, based on the loss points of charged fusion products reckoned by Lorentz orbit calculations. Energy- and time-resolved measurement of fusion product flux will progress in further understanding of energetic ion confinement in LHD.

Spectroscopic performance of Ni/4H-SiC and Ti/4H-SiC Schottky barrier diode alpha particle detectors

Advancement in the growth of 4H-SiC with low micropipe densities (∼ 0.11 cm-2) in achieving high pure epitaxial layers, enabled the development of high-resolution 4H-SiC alpha particle Schottky radiation detectors for harsh environments. In particular, the study considers two types of 4H-SiC radiation detectors having Ni and Ti as Schottky contacts. They are fabricated by depositing Ni and Ti on 25 μm thick n-type 4H-SiC by epitaxially growing on 350 μm thick conducting SiC substrates. Electrical characterization and alpha spectral measurements performed on Ni/4H-SiC and Ti/4H-SiC SBDs are reported in this work. The spectral measurements were carried out using 241Am alpha emitting radioactive source. Ni/ 4H-SiC Schottky detector showed a better spectral response with 22.87 keV FWHM (∼ 0.416%) at a reverse bias of 150 V for 5.48 MeV alpha particles while Ti/4H-SiC Schottky detector achieved a resolution of 38.25 keV FWHM (∼ 0.697%) at 170 V reverse bias. This work presented spectral broadening analysis to understand the various factors affecting the energy resolution of the detectors. The extracted charge collection efficiencies (CCEs) are approximately 99% in both the detectors. In addition, polarization effects are not noticed in any of the fabricated detectors. The diffusion length of minority carriers (Lp ) is computed based on the drift-diffusion model by fitting the CCE curve as a function of applied bias, and the values are close to 9 μm and 7 μm for Ni/4H-SiC SBD and Ti/4H-SiC SBD detectors, respectively. Annealing at 400°C for 5 minutes in N2 ambient resulted in resolution of 23.98 keV FWHM (∼ 0.436%) for Ni/4H-SiC SBD detector at -170 V and 36.21 keV FWHM (∼ 0.661%) for Ti/4H-SiC SBD detector at -150 V. Overall Ni/4H-SiC SBD detectors showed superior spectral characteristics and superior resolution when compared to Ti/4H-SiC SBD detectors. However, the Ti/4H-SiC SBD detector fabricated in this work performed better than the previously reported work on a similar device structure. Hence, future work aimed at improving resolution of radiation detectors could also consider Ti/4H-SiC SBDs along with Ni/4H-SiC SBDs.

Novel imaging technique for thermal neutrons using a fast optical camera

A novel imaging technique for thermal neutrons using a fast optical camera is presented. Thermal neutrons are reacted with 6Lithium to produce a pair of 2.73 MeV tritium and 2.05 MeV alpha particles, which in turn interact in a thin layer of LYSO crystal scintillator to produce a localized flash of light. These photons are directed by a pair of lenses to a micro-channel plate intensifier, and its output is connected to the optical camera, TPX3CAM. The results from the camera are reconstructed through a custom algorithm. Various cutting parameters were found through data analysis to eliminate the background, and they were shown effective in matching the simulated rate of the neutron source. The system is fast with 40 ns decay time and allows free-space light collection, both vastly enhances flexibility of neutron detection.

Development and performance of a secondary electron detector based on a MCP

Secondary electron detector (SED) is a key component used in the fission product yield experiment to mark the start time of fission events. The signal to noise ratio and timing characteristics has an important impact on the mass resolution for measuring fission fragments. In this paper, a novel design of secondary electron detector based on MCP was proposed to measure the secondary electrons emitted from fission target. Based on the alpha particles and the fission fragments emitted from 252Cf source, the response of SED and SCVD diamond are obtained by using a digitizer of 10 bit and 1 ​G samples/s. The rise time of alpha particles and fission fragments are 1.8 ns and 1.7 ns, while the pulse width of which is 4.5 ns and 9.7 ns, respectively. Using the time of flight method and digital constant fraction algorithm, the time resolution of "SED ​+ ​sCVD diamond detector" system for 6.1 ​MeV alpha particles from 252Cf is obtained as 242 ± 4.7 ps, while that of SED detector is about 171 ± 2.4 ps. The total transition length and time of secondary electron (SE) in the detector are 15.79 cm and 5.97 ns, respectively.

Etching and optical properties of 1–2 MeV alpha particles irradiated CR-39 radiation detectors

A comparison of track etch parameters at low energy alpha particles is presented, using the Lantrak and the Baryotrak CR-39 nuclear track detectors. Experimental data from literature, obtained through exposing CR-39 detectors at low energy alpha particles from a 241Am source and, subsequently, etching them in NaOH, KOH, and NaOH+ethyl alcohol aqueous solutions at 70°C and 80°C, have been numerically analyzed here. Radial etch rates of alpha particle etch pits have been determined, compared, and critically discussed for both CR-39 types. Ratios of alpha etch pit diameters and etch pit densities have also been examined as a function of etching time, showing no notable differences in the comparison between these two detectors. This study has been extended from the structural point of view by performing new Ultraviolet–visible (UV–Vis) and Raman spectroscopy measurements on non-irradiated, α-irradiated and α-irradiated/etched Lantrak and Baryotrak detectors. The direct band-gap energies have been determined and no significant differences have been observed in detectors subjected to different conditions. The Raman spectra show that the CH2 functional group has been decreased when comparing the non-irradiated/α-irradiated and α-irradiated/etched detectors, suggesting a degradation of the detectors due to alpha particle irradiation and also due to the different chemical etching treatments applied. The uncertainties have been determined and reported along with the results.

Development of a capillary plate based fiber-structured ZnS(Ag) scintillator

Silver-doped zinc sulfide (ZnS(Ag)) is an opaque powder scintillator that is mainly used for detection or imaging of charged particles such as alpha particles. Since ZnS(Ag) is not transparent, the thickness of ZnS(Ag) was limited to ∼10 μm. If a thicker ZnS(Ag) scintillator could be developed, it would be useful for studies such as high-energy particle ion detection as well as beta particle or gamma photon detection. We developed a ZnS(Ag) fiber-structured scintillator using a capillary plate in which ZnS(Ag) powder was encapsulated in the capillaries. The thickness of the capillary plate was 400 μm, and the light produced in ZnS(Ag) escaped from the capillaries, spread through the transparent lead glass area, and reached the opposite side of the plate; consequently, the opaque character and absorption of light could be avoided. The amount of light emitted from the capillary plate based fiber-structured ZnS(Ag) was almost the same as that of a commercially available ZnS (Ag) film, but the detection efficiency was about 1/5 (∼ 20%). The amount of light emitted from beta particles and gamma photons per MeV was less than 1% of that from alpha particles. The spatial resolution of the developed capillary plate based fiber-structured ZnS(Ag) scintillator for 5.5 MeV alpha particles was ∼200 μm FWHM. Imaging of the slits and light spots from alpha particles could be achieved with the developed scintillator combined with an electron-multiplied charge-coupled device (EM-CCD) camera. The developed capillary plate based fiber-structured ZnS(Ag) will be useful for detecting high-energy particle ions.

Dose Response Curve Using Chemically Induced PCC Assay in Peripheral Cells Irradiated In-vitro to 5 MeV Alpha Particles Emitted From Radon Source

Bio-dosimetry is defined as estimation of dose received by individuals based on biological end points induced by ionizing radiation. By using cytogenetic assay, it is possible to quantify the absorbed dose. High linear energy transfer (LET) radiation produces dense ionizations along their path and causes more clustered DNA damage compared to low LET. Radon is a natural radioactive element present in the atmosphere mainly produced during decay of uranium. The main objective of the present study is to construct dose response curve by using Premature Chromosome Condensation (PCC) techniques in blood cells exposed in-vitro to radon exposure. Blood samples were drawn from healthy non-smokers (n=4), aged between 28 to 42 years and exposed to twenty doses of radon ranged between 0 to 5.5 mGy. A total of about 24000 metaphase spreads were counted to find the DNA damages include ring chromosomes (RC), dicentric chromosomes (DC) and acentric fragments (AF). As the dose increases gradual increase was observed in RC, DC and AF with the slope of 0.001, 0.005 and 0.064 respectively. So far, no calibration reference curve was generated for low dose radon using chemically induced PCC assay and hence this study is considered as first of its kind.