Notre Dame, USA, where he had originated the Ganguly-Magee theory in Radiation Chemistry. During Ganguly's career in the BARC, Vikram A. Sarabhai selected him to lead the process of formation of the Ministry of Environment. The device was of the implosion-type design and had a close resemblance to Fat Man, the American nuclear bomb detonated over Nagasaki in 1945. The implosion system was assembled at the Terminal Ballistics Research Laboratory (TBRL) of the DRDO in Chandigarh. The detonation system was developed at the High Energy Materials Research Laboratory (HEMRL) of the DRDO in Pune, Maharashtra State. The 6 kg of plutonium came from the CIRUS reactor at BARC. The neutron initiator was of the polonium–beryllium type and code-named Flower. V.K. Iya of BARC was on the team which developed the neutron initiator. The entire nuclear bomb was engineered and finally assembled by Indian engineers at Trombay before transportation to the test site. Nuclear weapon design Cross-section The fully assembled device had a hexagonal cross section, 1.25 metres in diameter, and weighed 1400 kg. The device was mounted on a hexagonal metal tripod, and was transported to the shaft on rails which the army kept covered with sand. The device was detonated when Pranab R. Dastidar pushed the firing button at 8.05 a.m.; it was in a shaft 107 m under the army Pokhran test range in the Thar Desert, Rajasthan. Controversy regarding the yield The nuclear yield of this test still remains controversial, with unclear data provided by Indian sources, although Indian politicians have given the country's press a range from 2 kt to 20 kt. The official yield was initially set at 12 kt; post-Operation Shakti claims have raised it to 13 kt. Independent seismic data from outside and analysis of the crater features indicate a lower figure. Analysts usually estimate the yield at 4 to 6 kt, using conventional seismic magnitude-to-yield conversion formulas. In recent years, both Homi Sethna and P. K. Iyengar have conceded the official yield to be an exaggeration. Iyengar has variously stated that the yield was 8–10 kt, that the device was designed to yield 10 kt, and that the yield was 8 kt "exactly as predicted". Although seismic scaling laws lead to an estimated yield range between 3.2 kt and 21 kt, an analysis of hard rock cratering effects suggests a narrow range of around 8 kt for the yield, which is within