R K Choudhury
Articles written in Pramana – Journal of Physics
Volume 6 Issue 2 February 1976 pp 64-76 Nuclear And Particle Physics
Studies of mass and energy correlations in thermal neutron fission of U-235 accompanied by long range alpha particles
R K Choudhury S S Kapoor D M Nadkarni P N Rama Rao S R Srinivas Murthy
Several characteristics of fission accompanied by long range alpha particles (LRA) have been studied in the thermal neutron induced fission of235U. The kinetic energies of fission fragments and the LRA were measured with a back-to-back ionization chamber and semiconductor detectors respectively. The kinetic energies of the two fragments and the LRA in LRA fission, along with the energies of pair fragments in the normal binary fissions, were recorded event by event on a magnetic tape by means of a four-parameter data acquisition system. The data were analysed to study the dependence of different quantities in LRA fission on the fragment mass ratio, LRA energy and the total kinetic energy of the fission fragments. It is seen that the most probable energy of LRA increases significantly for near symmetric mass divisions. The total kinetic energy for all mass ratios in LRA fission is found to be (2.6±0.7) MeV larger than that in binary fission. The difference in the total kinetic energies in LRA and binary fissions is seen to be dependent on mass ratio. This result may suggest that the scission configuration in LRA fission is different for different mass ratios. Correlations between the fission fragment and LRA energies have been studied for several mass ratios. It is seen that the most probable fragment kinetic energy
Volume 8 Issue 4 April 1977 pp 315-321 Nuclear And Particle Physics
Yields and energy spectra of light charged particles emitted in neutron induced fission of235U
B Krishnarajulu G K Mehta R K Choudhury D M Nadkarni S S Kapoor
The yields and energy spectra of light charged particles emitted in the fission of235U have been measured in the neutron energy range of 100 keV to 1 MeV. The yield of long range alpha particles is found to increase around 200 keV neutron energy compared to thermal fission. A low energy component observed in the energy spectrum was assigned to the tritons emitted in fission. The yield of this triton component is seen to have a marked increase around 500 keV. These results indicate that LCP yield is influenced by the transition state level characteristics.
Volume 8 Issue 4 April 1977 pp 322-327 Nuclear And Particle Physics
Prompt gamma ray multiplicity distributions in spontaneous fission of252Cf
V S Ramamurthy R K Choudhury J O Mohankrishna
The shape parameters of the multiplicity distribution of prompt gamma rays emitted in spontaneous fission of252Cf were obtained using the multiple coincidence technique. The multiplicity distribution is well represented by a Gaussian distribution. Assuming the average number of prompt gamma rays emitted per fission to be 10.3, the standard deviation of the multiplicity distribution was estimated to be 4.2±0.4. The variation of the standard deviation of the multiplicity distribution has also been obtained as a function of kinetic energy of one of the fragments and was found to exhibit a strong zigzag dependence on the single fragment kinetic energy. The results have been discussed on the basis of the emission mechanism of prompt gamma rays in fission.
Volume 9 Issue 6 December 1977 pp 623-627 Nuclear And Particle Physics
Multiplicity distribution of prompt gamma rays in spontaneous ternary fission of252Cf
V S Ramamurthy R K Choudhury J C Mohana Krishna
The first and the second moments of the multiplicity distribution of prompt gamma rays in spontaneous ternary fission of252Cf have been measured by the multiple coincidence technique. While both these moments were found to be nearly independent of the energy of the light charged particle accompanying the fission fragments, the width of the multiplicity distribution was larger than that in the case of normal binary fission by about 20%.
Volume 34 Issue 4 April 1990 pp 1- Rapid Communications
Detection limits of high temperature superconducting materials on various substrates by energy dispersive X-ray fluorescence and proton induced X-ray emission methods
M Lal H N Bajpai D Joseph R K Choudhury
Application of energy dispersive X-ray fluorescence (EDXRF) and proton induced X-ray emission (PIXE) methods has been demonstrated for determining the elemental composition of thin film superconducting materials. The results of analysis carried out by EDXRF method have been compared with those obtained by PIXE method. Thin films of YBa2Cu3O7 superconducting material were deposited on various substrates such as thin mylar sheet and thick substrates of SrTiO3, MgO and Al2O3. In thin backing the minimum detection limits obtained for Cu, Y, Ba by the PIXE method are 20 ng, 70 ng and 800 ng respectively and the corresponding values by the EDXRF method are 3000 ng, 600 ng and 1000 ng. Detection limits for samples on thick backings deteriorated to a large extent by both methods.
Volume 40 Issue 4 April 1993 pp 299-309
Prompt neutron emission spectra and multiplicities in the thermal neutron induced fission of235U
M S Samant R P Anand R K Choudhury S S Kapoor K Kumar D M Nadkarni A Saxena
The emission spectra of prompt fission neutrons from mass and kinetic energy selected fission fragments have been measured in235U(
Volume 41 Issue 4 October 1993 pp 339-344
Sub-barrier fission fragment angular distributions for the system19F+232Th
S Kailas A Navin A Chatterjee P Singh A Saxena D M Nadkarni D C Biswas R K Choudhury S S Kapoor
The measurements of fission fragment angular distributions for the system19F+232Th have been extended to the sub-barrier energies of 89.3, 91.5 and 93.6 MeV. The measured anisotropies, within errors are nearly the same over this energy region. However, the deviation of the experimental values of anisotropies from that of standard statistical model predictions increases as the bombarding energy is lowered.
Volume 42 Issue 2 February 1994 pp 123-133
Mass asymmetry dependence of fusion time-scales in11B+237Np and12C,16O,19F+232Th reactions in a dynamical trajectory model
Kiran Kumar R K Choudhury A Saxena
Dynamical trajectory calculations were carried out for the reactions of11B+237Np and12C,16O and19F+232Th, having mass asymmetries on either side of the Businaro-Gallone critical mass asymmetry αBG, in order to examine the mass asymmetry dependence of fusion reactions in these systems. The compound nucleus formation times were calculated as a function of the partial wave of the reaction for all the systems. This study brings out that for systems with α<αBG, the formation times are significantly larger than for α>αBG, which is caused by the dynamical effects involved in the large scale shape changes taking place in the fusion process as well as due to the interplay between the thermal and the collective motion during the collision process. The calculated time scales are comparable to the experimental values derived from the pre-fission neutron multiplicity measurements.
Volume 44 Issue 2 February 1995 pp 177-182
Deep inelastic collisions of32S +27Al reaction at 130 MeV bombarding energy
R K Choudhury D M Nadkarni V S Ambekar B V Dinesh A Saxena M S Samant D C Biswas L M Pant
The32S +27Al reaction was studied to investigate the deep inelastic collisions at a bombarding energy of 130 MeV which is well above the Coulomb barrier. The energy distributions of the binary decay products of 6⩽
Volume 53 Issue 3 September 1999 pp 521-528 Nuclear Reactions At Near And Sub-Barrier Energies
Some aspects of heavy ion fusion-fission dynamics
D V Shetty R K Choudhury B K Nayak D M Nadkarni S S Kapoor
Study of heavy ion induced fusion-fission reactions at near and below barrier energies has attracted a great deal of attention in recent years, due to the observations of anomalous features in the fragment angular distributions for many target-projectile systems. Additionally there are also measurements of the fragment spin distributions and time-scales of the fusion-fission reactions, which have provided important information on the dynamics of these processes. In the present paper, the emphasis would be to highlight some of the recent experimental findings and their implications on the dynamics of the fusion-fission reactions in heavy ion collisions at near and above barrier energies.
Volume 57 Issue 2-3 August 2001 pp 355-369
First results from RHIC-PHENIX
Tarun Kanti Ghosh K Adcox S S Adler N Ajitanand Y Akiba J Alexander L Aphecetche Y Arai S H Aronson R Averbeck T C Awes K N Barish P D Barnes J Barrette B Bassalleck S Bathe V Baublis A Bazilevsky S Belikov F G Bellaiche S T Belyaev M J Bennett Y Berdnikov S Botelho M L Brooks D S Brown N Bruner D Bucher H Buesching V Bumazhnov G Bunce J Burward-Hoy S Butsyk T A Carey P Chand J Chang W C Chang L L Chavez S Chernichenko C Y Chi J Chiba M Chiu R K Choudhury T Christ T Chujo M S Chung P Chung V Cianciolo B A Cole D G D’Enterria G David H Delagrange A Denisov A Deshpande E J Desmond O Dietzsch B V Dinesh A Drees A Durum D Dutta K Ebisu Y V Efremenko K El Chenawi H En’yo S Esumi L Ewell T Ferdousi D E Fields S L Fokin Z Fraenkel A Franz A D Frawley S-Y Fung S Garpman T K Ghosh A Glenn A L Godoi Y Goto S V Greene M Grosse Perdekamp S K Gupta W Guryn H-Å Gustafsson J S Haggerty H Hamagaki A G Hansen H Hara E P Hartouni R Hayano N Hayashi X He T K Hemmick J Heuser J C Hill D S Ho K Homma B Hong A Hoover T Ichihara K Imai M S Ippolitov M Ishihara B V Jacak W Y Jang J Jia B M Johnson S C Johnson K S Joo S Kametani J H Kang M Kann S S Kapoor S Kelly B Khachaturov A Khanzadeev J Kikuchi D J Kim H J Kim S Y Kim Y G Kim W W Kinnison E Kistenev A Kiyomichi C Klein-Boesing S Klinksiek L Kochenda D Kochetkov V Kochetkov D Koehler T Kohama A Kozlov P J Kroon K Kurita M J Kweon Y Kwon G S Kyle R Lacey J G Lajoie J Lauret A Lebedev D M Lee M J Leitch X H Li Z Li D J Lim M X Liu X Liu Z Liu C F Maguire J Mahon Y I Makdisi V I Manko Y Mao S K Mark S Markacs G Martinez M D Marx A Masaike F Matathias T Matsumoto P L McGaughey E Melnikov M Merschmeier F Messer M Messer Y Miake T E Miller A Milov S Mioduszewski R E Mischke G C Mishra J T Mitchell A K Mohanty D P Morrison J M Moss F Mühlbacher M Muniruzzaman J Murata S Nagamiya Y Nagasaka J L Nagle Y Nakada B K Nandi J Newby L Nikkinen P Nilsson S Nishimura A S Nyanin J Nystrand E O’Brien C A Ogilvie H Ohnishi I D Ojha M Ono V Onuchin A Oskarsson L Österman I Otterlund K Oyama L Paffrath A P T Palounek V S Pantuev V Papavassiliou S F Pate T Peitzmann A N Petridis C Pinkenburg R P Pisani P Pitukhin F Plasil M Pollack K Pope M L Purschke I Ravinovich K F Read K Reygers V Riabov Y Riabov M Rosati A A Rose S S Ryu N Saito A Sakaguchi T Sakaguchi H Sako T Sakuma V Samsonov T C Sangster R Santo H D Sato S Sato S Sawada B R Schlei Y Schutz V Semenov R Seto T K Shea I Shein T-A Shibata K Shigaki T Shiina Y H Shin I G Sibiriak D Silvermyr K S Sim J Simon-Gillo C P Singh V Singh M Sivertz A Soldatov R A Soltz S Sorensen P W Stankus N Starinsky P Steinberg E Stenlund A Ster S P Stoll M Sugioka T Sugitate J P Sullivan Y Sumi Z Sun M Suzuki E M Takagui A Taketani M Tamai K H Tanaka Y Tanaka E Taniguchi M J Tannenbaum J Thomas J H Thomas T L Thomas W Tian J Tojo H Torii R S Towell I Tserruya H Tsuruoka A A Tsvetkov S K Tuli H Tydesjö N Tyurin T Ushiroda H W van Hecke C Velissaris J Velkovska M Velkovsky A A Vinogradov M A Volkov A Vorobyov E Vznuzdaev H Wang Y Watanabe S N White C Witzig F K Wohn C L Woody W Xie K Yagi S Yokkaichi G R Young I E Yushmanov W A Zajc Z Zhang S Zhou
The PHENIX experiment consists of a large detector system located at the newly commissioned relativistic heavy ion collider (RHIC) at the Brookhaven National Laboratory. The primary goal of the PHENIX experiment is to look for signatures of the QCD prediction of a deconfined high-energy-density phase of nuclear matter quark gluon plasma. PHENIX started data taking for Au+Au collisions at √
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