PHYS01200804001 Sohrab Abbas - Homi Bhabha National Institute

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Research A, 634 (2011) S41. [9] S. Abbas, A. G. Wagh, M. Strobl and W. Treimer, Journal of Physics (CS), 251 (2010) 012073. [10] S. Abbas, A. G. Wagh, and W. Treimer, Sol. St. Phys. (India), 53 (2008) 555. [11] A. G. Wagh, S. Abbas, and W. Treimer, Sol. St. Phys. (India) 53 (2008) 553. [12] A. G. Wagh, S. Abbas, and W. Treimer, Pramana- J. Phys. 71 (2008) 1171. [13] A. G. Wagh, S. Abbas and W. Treimer, BENSC Experimental reports 2007(HMI, Germany, 2008) 223. [14] A. G. Wagh and S. Abbas, Sol. St. Phys. (India), 51 (2006) 353. [15] A. G. Wagh, S. Abbas, M. Strobl and W. Treimer, BENSC experimental reports 2006 (HMI, Germany, 2007) 22. [16] S. Abbas, A. G. Wagh, M. Strobl and W. Treimer, Sol. St. Phys. (India), 52 (2007) 441. [17] S. Abbas, A. G. Wagh, R. Loidl, H. Lemmel and H. Rauch, AIP Conf. Proc., 1349 (2011) 501. [18] A. G. Wagh, S. Abbas R. Loidl, H. Lemmel and H. Rauch, ILL Experimental reports 3-15-58, 2009 (Grenoble, France, 2010). [19] S. Abbas and A. G. Wagh, Pramana J-Phys., 63 (2004) 375. [20] A. G. Wagh and S. Abbas, J. Res. Natl. Stad. Technol., 110 (2005) 237. [21] A. G. Wagh, S. Abbas T. Potocar, H. Lemmel and H. Rauch, ILL Experimental reports 3-15-61, 2011 (Grenoble, France, 2012) to be published. [22] S. Abbas, A. G. Wagh, T. Potocar, H. Lemmel and H. Rauch, AIP Conf. Proc. (2011) submitted. V
CHAPTER 1 Introduction 1.1 Introduction Particle-wave duality forms the basis for optics and the dynamical diffraction of neutrons [1-5]. De Broglie’s discovery [6] of the fundamental fact that a particle of mass m and velocity v behaves like a wave of wavelength given by h , (1) m v paved the way for the unification of matter and radiation. Here symbol h signifies the Planck constant. Davisson-Germer [7] and Thomson [8] provided a firm experimental footing to the matter wave hypothesis by observing Bragg diffraction [9] of electrons from a Ni-single crystal. Chadwick’s discovery of the neutron in 1932 [10] motivated Mitchell and Powers [11] to experimentally verify its wave nature by employing the Bragg diffraction of neutrons (from an MgO single crystal) with the neutron beam extracted from a Ra–Be source embedded in a paraffin moderator. However, the biggest and the most drastic boost to development of neutron physics came with Fermi’s operation of a nuclear reactor in 1942. Neutrons produced by U 235 fission in a research reactor have an average energy of 2MeV. They are slowed to thermal energies in a moderator (such as graphite, beryllium, heavy or light water) surrounding the fuel. The peak core flux of research reactors is typically in the range of 10 14 cm −2 s −1 to 10 15 cm −2 s −1 . To maximize the neutron flux density, it is necessary to increase the fission rate per unit volume, but the power density is limited by heat transfer and material properties [12]. In spallation sources, high intensity (mA) proton beams (typically) of energies in the GeV range strike a high Z target, producing approximately 20 neutrons per proton with energies in the fast and epithermal region. Existing 1
Page 1: Studying neutron dynamical diffract
Page 4 and 5: DECLARATION I, hereby declare that
Page 6 and 7: ACKNOWLEDGEMENTS I sincerely, thank
Page 8 and 9: Fig.10 Boundary conditions on wave
Page 10 and 11: Fig.28 Theoretical curves for Si {1
Page 12 and 13: sample. Least-squares fit to the sa
Page 14 and 15: Fig.62 Interference contrast and av
Page 16 and 17: 3.4 Experimental 49 3.5 Results and
Page 18 and 19: SYNOPSIS The present thesis aims to
Page 20 and 21: analytic expressions for intensity
Page 24 and 25: spallation sources yield peak neutr
Page 26 and 27: SU(2) phase, and separation of geom
Page 28 and 29: [33-34,48]. The bi-refracting natur
Page 30 and 31: application of the dynamical theory
Page 32 and 33: I. One of the major disadvantages o
Page 34 and 35: nuclear physics very important as i
Page 36 and 37: potential for most nuclei in spite
Page 38 and 39: Due to the rapid strides made latel
Page 40 and 41: for a positive value of b c i.e. fo
Page 42 and 43: k b k O H . ni sin( B S) . (18)
Page 44 and 45: factor exp(-W). The centre, θ C ,
Page 46 and 47: exploiting multiple successive iden
Page 48 and 49: We shall confine our discussion hen
Page 50 and 51: The depth Z is measured from the in
Page 52 and 53: wings (large-y regions). The freque
Page 54 and 55: expressed as T(y, t )R(y, t )R(
Page 56 and 57: studies. With such beams, the and
Page 58 and 59: CHAPTER 3 Neutron forward diffracti
Page 60 and 61: eing the separation of points M and
Page 62 and 63: 3.1 Neutron forward diffraction Con
Page 64 and 65: excited by the incident wave (Fig.1
Page 66 and 67: Therefore, the forward diffracted i
Page 68 and 69: Fig.15 Calculated cr and I O for a
Page 70 and 71: (1 I ) D tan b . ID cot( B S)
Page 72 and 73:
Fig.18 Experimental layout to measu
Page 74 and 75:
Fig.20 Bragg reflection intensity f
Page 76 and 77:
fraction I O through the Bragg pris
Page 78 and 79:
Fig.22 Experimental (points) and th
Page 80 and 81:
Table 2: Observed deflection sensit
Page 82 and 83:
total reflectivity domain. These ar
Page 84 and 85:
Here the term C() accounts for the
Page 86 and 87:
Fig.28 Theoretical curves for Si {1
Page 88 and 89:
I H (θ H ) peaks of 0.18 height an
Page 90 and 91:
other with a compression factor lim
Page 92 and 93:
an overall compression factor of 14
Page 94 and 95:
4.3 Experimental 4.3.1 Bragg prism
Page 96 and 97:
4.3.2 Experiment The experiment was
Page 98 and 99:
Fig.38 Bragg reflection rocking cur
Page 100 and 101:
4.4 Applications of novel SUSANS se
Page 102 and 103:
Fig.42 First Q ~ 10 -6 Å -1 SUSANS
Page 104 and 105:
2 (1) -(δk i .Δ i ) /2 Γ (Δ) =
Page 106 and 107:
2 I( ) A( ) . (76) The least squa
Page 108 and 109:
Fig.46 Analyser rocking curve for a
Page 110 and 111:
This instrument was also employed t
Page 112 and 113:
Fig.48 Theoretical flat-topped angu
Page 114 and 115:
difference between the two neutron
Page 116 and 117:
Fig.52 Phase dispersion in a 26.5 m
Page 118 and 119:
the beam and remains visible up to
Page 120 and 121:
cos bc 4NDd1 1 2cot 2 III 2 2
Page 122 and 123:
yield about an order of magnitude r
Page 124 and 125:
The refractive index, n = (1-Nb c
Page 126 and 127:
with a white, and hence high-intens
Page 128 and 129:
proposed dual sample. The dual samp
Page 130 and 131:
The experiment was performed with =
Page 132 and 133:
Fig.59 Typical interferograms for p
Page 134 and 135:
Fig.63 Path I, II and I-II phases d
Page 136 and 137:
Fig.65 Average intensity with the s
Page 138 and 139:
Fig.69 New metrological mapping of
Page 140 and 141:
Si at 26.2 o C, applying a correcti
Page 142 and 143:
selected asymmetric Bragg prism may
Page 144 and 145:
III. High precision determination o
Page 146 and 147:
REFERENCES [1] H. Rauch and S. Wern
Page 148 and 149:
[36] J. S. Nico and W. M. Snow, Ann
Page 150 and 151:
[67] V. F. Sears, Can. J. Phys., 56
Page 152 and 153:
[97] A. Cabello, S. Filipp, H. Rauc
Page 154 and 155:
[127] A. Ioffe, D. L. Jacobson, M.
Page 156:
2009, (Grenoble, France, 2010) 3-15
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PHYS01200804001 Sohrab Abbas - Homi Bhabha National Institute

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