# RESEARCH CENTERS

# List of Instruments in Radiation Physics Lab

Sl. No. | Name of Instrument |
---|---|

1 | NaI (Tl) Gamma Spectrometer |

2 | Alpha Counter Beta Counter |

3 | Micro-R Survey Meter |

4 | Personal Computer |

5 | Hot Air Oven |

6 | Electronic Balance |

7 | Computer Accessories |

8 | High Volume Air Sampler |

9 | UPS |

10 | Radioactive Standard Sources |

11 | Magnetic Stirrer |

12 | IR Lamp |

13 | Anion Exchange Resin Column Set up |

14 | Fluoriemeter |

15 | Radon measurement system |

# Instruments and their specifications

##### PC Coupled Gamma Spectrometer (3” ×3”) & (5” ×5”)

Para Electronics (India) Pvt. Ltd. Model: NETS-3 / MU, 1 K Channel MCA, Spectroscopy system operating on 230V, 50 Hz, AC. NaI (Tl) Detector: 3” ×3” thick flat detector mounted on 3” dia PMT with mu metal shield, PMT based pre amplifier model NETS-0m, Lead Shield with 50 mm thickness.

##### Alpha Counter

Pla Electro Appliances Pvt.Ltd. Microcontrolled based radiation counting system Type CS- 201, Detector PEA Alpha Probe Type PSP 647/ D EHT set- 800V DC.

##### Beta Counter

Pla Electro Appliacnes Pvt. Ltd. Type CS 101L, Sr.NI o. -048, Detector PEA G.M Probe, Type G.P 40, Lead Castle Type P1705 m

##### Micro- R Survey meter

Type UR 705, Nucleonix make, Detector – 1” × 1” Na (Tl) Scintillator, 1” PMT, Accuracy- better than +/- 10%, Dose rate (0-10) mR/h in three ranges (0-100), (0-1000), and (0-10K), Sensitivity- 1 micro –R/h.

##### High Volume Air Sampler

Model TFIA, Make Staplex, USA. 220-240 V AC/DC, 50-60 Hz.

##### Hot Air Oven

Labline make oven, outer wall-mild steel sheet powder coated, inner chamber- Aluminium/ Stainless steel, Temperature range- + 500 C to 2500C, Control Accuracy +10C

##### Analytical Balance

Make- Precisa (Switzerland), Model- XB 12 A, Capacity – 120g, Accuracy- 0.0001g, Display- Fluorescent , Calibration- Internal, Pan Size- 80mm dia.

##### Magnetic Stirrer

Remi Magnetic Stirrer of 1L capacity with hot plate, Temperature from ambient up to 2500C, Thermostatic control with an accuracy of +/-10C

Doubled walled inside stainless steel and outer made of mild steel duly painted, to work on 220/230V

##### Radioactive Standard Sources

BRIT, Mumbai supplied set of radioactive gamma sources of 60Co, 57Co, 137 Cs, 22Na, 133Ba

##### Anion Exchange Resin Column Set Up

##### IAEA Radioactive Standards

# Chaos and Nonlinear Dynamics Lab

Chaos and Nonlinear Dynamics is one of the major areas of research in the Department of Physics, The Cochin College. K. P. Harikrishnan, Associate Professor, in the Department has been recognized as the Research Guide in the field of Chaos and Nonlinear Dynamics by M. G. University. A Major Research Project with K. P. Harikrishnan as the Principal Investigator is currently ongoing in the Department in the area of Chaos and Nonlinear Dynamics.

# Details of Projects:

**Nature of the Project:** Major Research project

**Sponsoring Agency:** Department of Science & Technology (DST), Govt. Of India.

**Title of the Project:** Study and Characterisation of Complex Networks based on Nonlinear Time Series Analysis Tools.

**Principal Investigator:** K. P. Harikrishnan

**Period of the Project:** 2013 – 2016.

**Name of JRF:** Rinku Jacob

**National Research Collaboration:**

The Department has research collaboration with the Inter University Centre for Astronomy and Astrophysics (IUCAA), Pune since 2000, with K. P.Harikrishnan being the Visiting Associate of IUCAA.

In this collaboration, study and characterization of light curve from Black Hole systems and Variable Stars using tools of Nonlinear Time Series Analysis is currently going on. Prof. Ranjeev Misra from IUCAA and Prof. G. Ambika from IISER, Pune are also involved in this collaborative project.

**STUDIES ON THE MODULATED NONLINEAR PROCESSES AND COUPLED MAP LATTICES-Minor Research Project approved by the U.G.C **

Ref. No. _MRP(s)-1414/11-12/KLMG011/UGC SWRO dated 10/07/2012

Summary of the findings

A variant of the discrete Lotka-Voltera model was taken for detailed study. This is of great interest because of co-existence and evolution of different species in an ecosystem has been a topic of interest for ecologists as well as mathematicians for many decades.

The standard version of the Lotka-Voltera model may be written as

Xn+1=axn(1-xn)-byn

Yn+1=-cyn+dxnyn

Where xn and yn are prey and predator population densities respectively at the discrete time step n. Parameter a represents the intrinsic growth of the prey.

We use a modified model of the following form

Xn+1=a xn(1-xn)-bynxn

Yn+1=-c yn+(1+λbxn)yn

The second term in the above equations describe the prey predator interactions which are favourable to the predator and fatal to the prey. The second term in the first equation is a measure of the efficiency of the predation and the second term in the second equation is a measure of how effectively the predator can transfer the advantage of predation for increasing its population. The asymptotic behavior of the system is now controlled by all the four parameters a, λ, b and c and the model captures most of the dynamic features of the standard model. Moreover it has the added advantage that the evolution and the survival of the predator can now be represented in terms of a threshold value of λ for each b and c and hence the model may be of more interest for ecologists. A detailed linear stability analysis of the system was carried to identify the parameter range of the periodic regime. The following conclusions we arrived from our detailed analysis.

The predator and prey population are always synchronized except when the extinction of predator occurs

If the natural growth rate of prey is very small (a<1) both prey and predator tend to extinction For every a>1, there is a threshold value of λ, λth below which the predator gets extinct and the dynamics of prey is governed by the logistic map. For a given pair of (c, b) the value for λth rapidly decrease as a increases from 1 and almost saturates as a->4 (λth =λ threshold)

For a given a, the value of λth is found to be directly proportional to c/b. thus the value of c has to be small or correspondingly b should be large for a better chance of survival of the predator

Interestingly for a given (a, c) if the value of b is less, the predator can still survive if the conversion factor λ can be increased.

As the value of a and λ are increased there is a general pattern of bifurcations as the asymptotic states passes through a limit cycle, periodic window, chaotic oscillations and finally escape through a boundary crisis. The general pattern is independent of the values of b and c but the range of domains of all the regimes depend on their values.

# List of Research Publications:

1) K. P. Harikrishnan, R. Misra and G. Ambika, Search for Deterministic Nonlinearity in the Light Curves of the Black Hole System GRS 1915 + 105, Chaotic Modeling and Simulation, Vol. 3, (2012), p.477

2) K. P. Harikrishnan, R. Misra and G. Ambika, Revisiting the box counting algorithm for the correlation dimension analysis of hyperchaotic time series, Commun. Nonlinear Sci. and Numerical Simulations, Vol. 17, (2012), p. 263

3) K. P. Harikrishnan, R. Misra and G. Ambika, Nonlinear Time Series Analysis of the Light Curves from the Black Hole System GRS 1915+105, Research in Astron. & Astrophys., Vol. 11, (2011), p.71

4) K. P. Harikrishnan, R. Misra, G. Ambika and R. E. Amritkar, Computing the multifractal spectrum from time series: An algorithmic approach, CHAOS, Vol. 19, (2010)143129

5) K. P. Harikrishnan, R. Misra, G. Ambika and R. E. Amritkar, Parametric characterization of a chaotic attractor using the two scale Cantor measure, Physica D, Vol. 239, (2010) p. 420

6) K. P. Harikrishnan, R. Misra and G. Ambika, Combined use of correlation dimension and entropy as discriminating measures for time series analysis, Comm. in Nonlinear Sci. and Numerical Simulations, Vol.14 (2009) p. 3608

7) K. P. Harikrishnan, R. Misra and G. Ambika, Efficient use of correlation entropy for analyzing time series data, Pramana“ J. Phys., Vol.72 (2009) p. 325

8) K. P. Harikrishnan and G. Ambika, Resonance Phenomena in discrete systems with bichromatic input signal : European Phys. Journal B, Vol.61 (2008) p.343.

9) K. P. Harikrishnan, G. Ambika and R. Misra, An algorithmic computation of correlation dimension from time series, Modern Phys. Letters B, Vol. 21 (2007) p. 129

10) K. P. Harikrishnan, R. Misra, G. Ambika and A. K. Kembhavi, A non-subjective approach to the GP algorithm for analyzing noisy time series : Physica D, Vol. 215 (2006) p. 137

11) R. Misra, K. P. Harikrishnan, G. Ambika and A. K. Kembhavi, The nonlinear behavior of the Black Hole system GRS1915+105 : The Astrophysical Journal, Vol. 643 (2006) p. 1114

12) G. Ambika, Kamala Menon and K. P. Harikrishnan, Noise induced resonance phenomena in coupled map lattices : European Phys. Journal B, Vol.49 (2006) p. 225

13) G. Ambika, Kamala Menon and K. P. Harikrishnan, Lattice Stochastic Resonance in coupled map lattice : Europhys. Letters, Vol. 73 (2006) p. 506

14) G. Ambika, Kamala Menon and K. P. Harikrishnan, Aspects of Stochastic Resonance in Josephson junction, bimodal maps and coupled map lattice : Pramana “ J. Phys. Vol.64 (2005) p.535

15) K. P. Harikrishnan and G. Ambika, Stochastic Resonance in a model for Josephson junction : Physica Scripta Vol.71 (2005) p.148

16) R. Misra, K. P. Harikrishnan, G. Ambika and A. K. Kembhavi, Chaotic Behaviour of the Blackhole System GRS 1915 + 105: Astrophysical Journal Vol.609 (2004) p.313

17) G. Ambika, N. V. Sujatha and K. P. Harikrishnan, Stochastic Resonance and Chaotic Resonance in Bimodal Maps: A case study : Pramana “ Journal of Physics Vol. 59 (2002) pg.539.

18) Presented a paper in the 5 International Conference (CMSIM “ 2012) held in Athens, Greece, June 12 – 15, 2012.

19) Presented a paper in the Seventh National Conference on Nonlinear Systems & Dynamics, at Indian Institute of Science Education and Research (IISER), Pune, from July 12 “ 15, 2012.

20) Presented a paper in the 4 International Conference (CMSIM “ 2011) held in Agios Nikolaos, Greece, May 31 “ June 3, 2011.

21) Presented a paper in the Sixth National Conference on Nonlinear Systems & Dynamics, School of Physics, Bharathidasan University, Thiruchirappally, from Jan 27 “ 30, 2011.

22) Presented a paper in the International Conference on Recent Deveopments in Nonlinear Dynamics, School of Physics, Bharathidasan University, Thiruchirappally, from Feb. 13 “ 16, 2008.

23) Presented a paper in the Fourth National Conference on Nonlinear Systems and Dynamics, Physical Research Laboratory, Ahmedabad, from Jan. 3 “ 5, 2008.

24) Presented a paper in the Third National Conference on Nonlinear Systems and Dynamics, RIASM, University of Madras, from Feb.6- 8, 2006.

25) Presented a paper in the Second National Conference on Nonlinear Systems and Dynamics, Aligarh Muslim Univ., from Feb.21-23, 2005.

26) Presented a paper in the First National Conference on Nonlinear Systems and Dynamics, I I T Kharagpur, from Dec.26-28, 2003.

27) Presented a paper in the VIII Ramanujan Symposium on recent developments in Nonlinear Systems, Feb. 14-16,2001 at the Ramanujan Institute for Advanced Study in Mathematics, University of Madras

28) Meeting on Chaos, Complexity and Information from Feb 1- 7,1997 at Dhvanyaloka, Mysore

29) Presented a paper at the Inter national Conference on Mathematical Modelling in Science and Technology held at I.I.T Madras (Aug 11- AUG 14,1988)