) PAGE 2 GASSEN As the result of ingenious experimentation and clever theorizing, it has been ly dgronstratos thit aters consist of a very sucll slectrically positive . : iq a3 sgyucled surrounded by s definite pattern o7 electrically negative cherge coupesed ef ae, For muny years it was thought that the, we mucned cons onsisted ef of protons (hydreger) in 1922 it has bean conclusively nuclei} andd electrons, but “ith the ciscovcery 9! neutrons as prevel that the atomic nucleus 1S] neeles scen ¢£9 ogee’ oiectron Xp ained by a& f 3 compesed of protons und newLLPGS « The fact that the c ta cacay has been tentatively in t he sc-called process of beta nhc not at process involving concepts t10 easy te describe to ths »minitiated. 4. Tan This explanation scculres a massless, or almost massless, partici: which has been called autringl, ¥ eisetion of igs tmesonsé (heavy electrons) has of the Cecp unknown, at which point we might Aaplropriately cake have we finvliy indivisibility or oll the process continue? Kenovhee.as therm scem to by too nr netfusdamentall “SUL wna entiv eirt of the lest exci. Loy Lacap mesa and pacibive chore, 66 tevsente fois, pobrtively a c2i aiuh £9 rodbem cosh! wer thes vere very coneunts of bo ecusenbreates and ccémie snesisgs of differmt nuclesr messes Lisotoces) could be soparoted. \ This aitviition woe sadiewthy chomged ly the aisecvery "nat certain nuclei covig abeoch fe llrcis ard brotk uj up into other nuclei and neutrons. more than ome It vas cuickiy neutron could be obtained from the " fission" started by one neutron. This Oper ¢ up the tremendous possibility cf£ +tthe "chain raaction" which has become a reality ae. g inuist ry . wil effects tae bie dinuus Nuclear rhrsies sudd enly emerged from the 44 muciear atomic toexb mage with miny applications te medicine end biology e described by my collcagves in this series of lectures. In my following lecture detet a of the prcceases of emission of alvna, beta and famme reys will ffi bbe radia described. sion dubesting srd measuring ct ! ; SeAsctrons. A description of the principle of operetion of deviece wili olso be civen. rc