The test experiments carried out at Flerov Laborarory of Nuclear Reactions, JINR are:
- 40Ar + 148Sm → 188−xHg + xn
- 40Ar + 166Er → 206−xRn + xn
- 48Ca + 242Pu → (Any element whose Z varies from 20-114)
The first and second nuclear reactions are complete fusion reactions neutron evaporation residues. In such types of reactions the product nucleus formed has no. of protons exactly equal to no. of protons of projectile particle + no. of protons of target nucleus. Here, all the nucleons participate in the reaction. While the third one is a Multi-Nucleon Transfer Reaction (MNTR). In such nuclear reactions different nuclides can be formed whose atomic no. ranges from atomic no. of projectile particle to sum of atomic nos. of projectile particle + target nucleus. This means not all nucleons participate in this reaction and can lead to formation of any possible product. The N/Z ratio of product nucleus can be higher or lesser than than the optimal ratio required for its stability (i.e. It can be proton rich or neutron rich). The U-400M cyclotron installed at FLNR, JINR is used to accelerate projectile particle (40Ar & 48Ca) to a very high velocity, with an energy ˜240 MeV (for 40Ar + 148Sm) and with energy ˜198 MeV (40Ar + 166Er). The high energetic projectile particle enters into the MASHA setup and induce a nuclear reaction by colliding with target material sputtered in rotating disc present in target box of MASHA facility. The products of nuclear reaction are isotopes of Hg (for 40Ar + 148Sm) and Rn (for 40Ar + 166Er and 48Ca + 242Pu) which are stopped by the absorber material of hot catcher. The absorber material is generally made up of thin film of graphite or carbon nanotubes which is heated to around 1800 − 2000oC by means of IR radiations coming out from poly-graphene heater as well as by a direct current passing through the absorber. This absorber stops the isotopic products of nuclear reaction, vaporizes them and their respective atoms diffuses through this absorber material into the vacuum volume of the hot catcher. Moving along the vacuum pipe, they reach the ECR ion source. This ECR ion source acts as an ionization chamber of MASHA setup where the atoms of gaseous isotopic products gets ionized to charge state Q=+1 and further they are accelerated with the help of three electrode system. (The three electrode system consists of one positive electrode, one negative electrode and one more negative electrode. Hence, an electric field is established from positive electrode to negative electrode. So, when a charged particle (here, ion) moves in the direction of electric field, it gets accelerated. The product isotopes are then separated by their M/Q ratio in the magnetooptical system of MASHA setup and at last they reach to the focal plane (F2) of the position sensitive Si detector and are detected at different strip numbers. (i.e. different isotopes are detected at different strip numbers). Now, the science is that the separated heavy nuclei undergoes α-decay to produce daughter nuclei and it’s exactly the alpha particles (with different energies) given out by both parent nucleus and its daughter nuclei which are detected at unique strip nos. of position sensitive Si detector. The detector used is a hybrid pixel detector of the TIMEPIX type, with high resolution and sensitivity which can detect even a single α or β particle. So, from the experimental data, we plot α-decay energy spectrum for those strips where an isotope was detected. From this spectrum (α-decay energy Vs. No. of counts) we analyze the prominent peaks and calculate their α-decay energy (Ea) values. The base peak with maximum no. of α particles (with common energy) is our point of interest as it could be any one of the separated nuclei. Now, using the table of nuclides, we find which isotope (of product of nuclear reaction) undergoes α-decay with energy very close to it. That particular isotope will be the one detected at a unique strip no. Ones, the isotope gets detected, its mass, alpha branching ratio, daughter nuclei can easily be investigated using the table of nuclides. In the same way we detect all the isotopes of an element which is the product of a nuclear reaction. In this work, we have also analyzed a two dimensional energy-position graph (called heatmap) for all three test experiments. It gives a clear understanding that which isotope is detected at which strip no. and corresponding to that particular isotope, how many alpha particles (counts) are detected with a common energy. This common energy is the energy of α-decay of that isotope.