National Facility for Neutron Beam Research [NFNBR]14.139.62.172/mumbai/nfnbr-book-R.pdfBhabha Atomic Research Centre, Mumbai, India 1 National Facility for Neutron Beam Research 2

1Bhabha Atomic Research Centre, Mumbai, India

National Facility for Neutron Beam Research 2

Neutrons for Condensed Matter Resarch 4

Single Crystal Diffractometer 6

Powder Diffractometer-1 8



Polarized Neutron Spectrometer 14

High-Q Diffractometer 16

Small-Angle Neutron Scattering Diffractometer 18

Double Crystal based SANS Instrument 20

Polarized Neutron Reflectometer 22

Spin Echo and Polarized Small Angle Neutron Scattering Instrument 24

Triple Axis Spectrometer 26

Quasi Elastic Neutron Spectrometer 28

Filter Detector Spectrometer 30

Neutron Radiography Facility 32

Neutron Detectors 34

Sample Environment Facilities 37

Contact Scientists 38

C o n t e n t s

2 Bhabha Atomic Research Centre, Mumbai, India

Neutron scattering at Trombay started

with the facility at Apsara reactor

(1 MW) in 1956, and then continued

with CIRUS (40 MW), which became

available in 1960 and then with the

present reactor Dhruva. Dhruva is a

100 MW natural uranium reactor with

peak thermal neutron flux of 1.8x1014

neutrons cm -2 s-1, tailor-made for

neutron scattering experiments with

tangential beam holes, through-tube,

provision for separate moderators for

cold and hot neutrons, guide-tube, etc.

Advanced instruments, fully automatic

in instrument control and data

acquisition modes have been installed

on various beam ports. State of the art

technology was used to design and

fabricate the spectrometers. 1-D and

2-D position sensitive detectors (PSD),

and associated electronics have also

been developed indigenously.

National Facility for Neutron Beam

Research (NFNBR) has been created as

a part of the Solid State Physics

Division (SSPD) during early nineties

to cater to the needs of the Indian

scientific community in the field of

neutron beam research. Scientists from

BARC, other DAE units, universities and

national laboratories are welcome to

use this facility through collaborative

reseach projects with SSPD scientists.

Many of these collaborations are being

supported by UGC-DAE Consortium

for Scientific Research, Board of

Research in Nuclear Sciences (BRNS)

and other agencies.

NationalFacility for

Neutron BeamResearch

International collaboration between neutron

beam research at BARC and other countries is

over four decades old. The first such

agreement was the “Indian-Philippines-IAEA

Agrement” signed during sixties, under

which BARC-built neutron instrument was

installed at Phillipines, and their scientists

were trained to use it. A more recent example

is the installation of a neutron spectrometer

at Bangladesh through IAEA in nineties.

Scientists from Phillipines, Korea, Indonesia,

Bangladesh, Vietnam, Malaysia and Egypt

have visited BARC to work on the neutron

instruments. A neutron instrument was

installed at the spallation neutron source at

Rutherford Appleton Laboratory in UK.

Scientists from SSPD avail advanced sources at UK, USA, Germany, France, Switzerland, Japan and other countries to carry

out front line research, and keep themselves up to date in this field.

Fig. 1. A panoramic view of CIRUS and DHRUVA reactors at BARC


General layout in the reactor hall and the guide-tube laboratory is shown in Fig. 2. There are four spectrometers at the

tangential beam lines, three at the ends of the through tube, two at the beam lines looking at the hot source, and four

instruments in the guide laboratory.

The present-day facilities include, single-crystal and powder diffractometers, polarization analysis spectrometer, Hi-Q

diffractometer, triple-axis & filter-detector spectrometers, quasi-elastic scattering spectrometer, all installed in the reactor

hall, and two small-angle scattering instruments, spin-echo spectrometer and reflectometer in the guide-tube laboratory.

80 K ice based cold neutron source and graphite at 1800 K hot source are under advanced stages of development.

Fig. 2. A layout of the neutron scattering instruments at Dhruva reactor

Fig. 3. A view of neutron scattering facilities inside the Dhruva reactor hall


Neutrons forCondensed

MatterResearch

The existence of a neutral particle

similar to the mass of a proton, was

hypothesized by Rutherford in 1920

and this was proved by the discovery

of neutron by J. Chadwick, a student

of Rutherford, in 1932. Since its

discovery, neutrons have been used

as a great probe for research in

condensed matter.

Due to its various special properties,

neutrons provide an insight about the

microscopic structures and dynamics

in a wide class of materials. When get

scattered by the materials, neutrons

can not only tell about the position of

an atom in that material but also

atomic movement with time.

Particle nature

• Mass = 1.67x10-27 Kg

• Spin = 1/2 Acts as a tiny magnet

• Magnetic moment = -1.913 μN

• Velocity [2200m/s for thermal

neutrons of energy 25 meV]

Neutron’s properties which make all these possible

. Wave-particle duality

. Compatible wavelength with the inter-atomic distances for thermal

neutrons

. Compatible energy with atomic excitation energies

. Deep penetration due to the charge neutrality

. Scattering contrasts between neighbouring elements in the periodic table

. Isotope specific scattering and absorption

. Magnetic moment and thus can interact with magnetic materials

. Simple interaction with nuclei (isotropic s-wave scattering). No angular

dependence of scattering amplitude for nuclear scattering unlike in the case

of x-ray.

Wave nature

• Diffraction and interference

pattern

• Measurable wavelength

• Measurable scattering length


Unlike for x-rays, the neutron

scattering power of elements

varies in a zigzag fashion with

respect to the atomic mass. Due

to this special property, neutron

can differentiate neighbouring

elements in a material and even

sees differently the different

isotopes of an element.

Neutrons also allow to probe

light atoms that are barely visible

with x-rays. The scattering

length of neutron for a few

isotopes of some elements

are negative. Hydrogen has a

negative scattering length

( -3.739 fm) while Deuterium

possess a positive scattering

length (6.671fm). Suitable

combination of materials with positive and negative scattering length can be used to tune the neutron scattering contrast.

Contrast matching experiments are used to obtain multi-level structures.

As the neutron does not carry any

electric charge, the neutron has no

electrostatic interaction with the

electron cloud of an atom. For this

reason, the neutron has a higher

penetration power comparable to

x-ray or electrons.

Neutron has a spin ½ and is sensitive

to the magnetic fields created by

unpaired electrons. In the magnetic

materials, the order in magnetic

structures and the interactions can be

obtained using neutron scattering.


Instrument parameters

Beam hole no. T1011

Monochromator Cu220

Wavelength 0.995

Scattering angle 0 o < 2θ < 90o

Flux at sample 5x105 n/cm2/sec

Detector BF3

Counter

The instrument is used to study a high

precision 3-dimensional structure of

materials, where hydrogen plays a

major role in either the stereochemistry

or the physical properties of the

materials. These include hydrates,

biomolecules, ferro-electrics, electro-

optic materials, etc.

The single crystal diffractometer is

located at T1011 beam line of the

Dhruva reactor. The crystal is rotated

about three Eulerian axes χ, φ and ω,and the detector is rotated about the

2θ axis. These four axes meet at a point,which is the centre of the sample

crystal. The χ circle is mounted on theω axis, while the φ circle is mountedon the χ-axis as shown in Figure.The crystal is mounted on the φ-axis.The geometry of axes mounting

enables any reciprocal lattice point to

be brought into the equatorial plane

of the diffractometer.

Single CrystalNeutron

Diffractometer

This Four Circle Eulerian geometrybased Single Crystal NeutronDiffractometer is used forthe studies on hydrogen-bondedcrystal structures.

Å


Selected examples

. Hydrogen bonding studies in bis(glycinium) oxalate

Fig.1. Showing the short hydrogen bond between glycinium and oxalate moiety

Single-crystal neutrondiffraction investigation ofbis(glycinium) oxalate wasundertaken in order to studyits hydrogen bondingnetwork, particularly the veryshort hydrogen bondbetween the glycinum andoxalate ions, indicated by theX-ray diffraction study. Thenon-existence of any phasetransition in these crystals wasattributed to the fact that theshort hydrogen bond inbis(glycinium) oxalate is asymmetric in nature, with no hydrogen disorder (Fig. 1). The potential energy landscape for theabove-mentioned H atom was found to have a single minimum closer to the glycinium ion. IR and Raman investigations ofthe title complex supported the above result.

Some references:

1. R. Chitra and R. R Choudhury, Acta Cryst. B 63, 497 (2007).2. R.Chitra, R.R. Choudhury and M.Ramanadham, Appl. Phys. A 74 (suppl.), S1576 (2002).3. R.R. Choudhury, R.Chitra and M.Ramanadham, Appl. Phys. A 74 (suppl.), S1667 (2002).

. Thiourea doped ammoniun dihydrogen phosphate

Fig. 2. Packing of the thiourea dopeddihydrogen phosphate

Thiourea Doped ADP (TADP) exhibits nonlinear optical property and thesecond harmonic generation efficiency of these crystals is three timesthat of pure ADP crystal. The single crystal neutron diffraction (Fig. 2)study of TADP gave cell parameters (a=b=7.531(3)Å,c=7.544(5)Å),which were found to be significantly greater from that of pure ADP atRT (a=b=7.502(1)Å,c=7.546(1)Å). This indicates that the dopantconcentration in the crystals is small but enough to bring changes in theoverall average structure. There is a significant lengthening of N-H—Ohydrogen bond in the Thiourea Doped ADP crystal.



Beam hole No. TT1015

Monochromator Si (422)

Monochromatortake –offangle (2θ

M) 60°

Wavelength 1.094 Å

Detector One linear He3

PSD, covers 30°in one PSDsetting

(Sin θ/λ )max 0.64 Å-1

Flux at sample 5x105 n/ cm2/sec

Scattering angle 5o < 2θ < 90o

Resolution (Δd/d) 1 %

The diffractometer is extensively used

for studying crystal and magnetic

structures in a large variety of systems.

These studies include titanates and

zirconates showing ferro/anti-

ferro-electric properties, alloys of

transition metals, rare-earths and

actinides (UCu2Ge

2, ErFe

2D

x etc.)

showing exotic magnetic properties,

ferrites exhibiting disordered

magnetic ordering, manganites

showing CMR behaviour, and

cobaltates showing coexistence of

ferro- and antiferromagnetism, etc.

PowderDiffractometer-1

This instrument is installed atThrough-tube beam hole no TT1015and has been used to carry out medium-resolution powder diffractionmeasurements on a variety ofmagnetic and nonmagnetic systems.

S.K. Paranjpe and Y. D. Dande, Pramana-J. Phys. 32, 793 (1989).S.K. Paranjpe and S. M. Yusuf, Neutron News 13, 36 (2002).


Neutron powder diffraction patterns of CaTiO3 (CT)

and Sr1-x

CaxTiO

3 (SCT) with x = 0.04 and 0.50. For

the CT and SCT (x=0.50) samples, superlattice linesare observed.

Temperature variation of I531

/ I006

for Sr1-x

CaxTiO

3 (SCT) with

x = 0.06 and 0.12. The antiferrodistortive phase transition isobserved around 300 K and 375 K for x = 0.06 and 0.12,respectively.

Some references:

1. V. G. Sathe et al., J. Phys.-Cond. Matter 10, 4045 (1998).2. R. Ranjan et al., J. Phys.-Cond. Matter 11, 2233 (1999).3. P. Raj et al., Phil. Mag. B 79, 1185 (1999).4. A. Das et al., J. Magn. Magn. Mat. 237, 41 (2001) .5. S. M. Yusuf et al., Phys. Rev. B 68, 104421(2003).

Selected examples

. Mixed Ferrites: Disordered Magnetic Systems: Magnetic ordering in Zn0.5

Co0.5

FeCrO4

The evolution of themagnetic structure factorwith temperature for (a)the (220) reflection and(b) the (222) reflectionfor Zn

0.5Co

0.5FeCrO

4.

Solid curves: The Brillouinfunctions

Difference neutron diffraction patterns at 40,20, and 15 K with respect to 200 K forZn

0.5Co

0.5FeCrO

4 showing the buildup of the

diffuse hump at ~20 K around a Q-value wherethe (200) Bragg peak is expected.

. Structural phase transition in ferroelectric materials



Beam hole no. T1013

Monochromator Ge (331)

Wavelength 1.249 Å

Beam size 4.0 cm x1.5 cm

Flux at sample 8.5x105 n/cm2/sec


Q range 0.4 – 9.4 Å-1

Δd/d ~ 0.8 %

Detector 5 PSDs (to beupgradedto 15 PSDs)

Sampleenvironment 10 – 300 K


This Powder diffractometeris a conventional medium resolutionneutron diffractometer. It is mainly used tostudy stuctural and magnatic ordering inpolycrystalline materials.

Powder diffractometer is a multi-PSD

based instrument covering Q-range

up to 9.4 Å-1. This instrument is being

extensively used by researchers all over

the country to study structural and

dimensional magnetic materials,

molecular magnetic materials and also

in studies of local structure

determination from disordered

crystalline systems.

magnetic transitions in alloys and

compounds. It has been used for

structural studies of a number of CMR

materials, ferro-electric materials, high

Tc materials, SOFC materials, low


Selected examples

. Low temperature structural phase transitions in NaNbO3

Material engineering of alkaline niobates like potassium sodium niobate and lithium sodium niobate with ultralarge piezo

response comparable to PZT have evoked considerable interest as the next generation eco-friendly lead free piezo ceramics

required for applications as transducers in cell phones, medical implants, etc. The end member NaNbO3 has an antiferroelectric

(AFE) structure at room temperature and exhibits an unusual complex sequence of temperature and pressure driven

structural phase transitions which are not clearly understood. Accurate characterization of the phase diagram of NaNbO3 is

essential for the design of new sodium niobate based ceramics required for applications. Powder neutron diffraction

studies have been used to understand the complex sequence of low temperature phase transitions of NaNbO3 in the

temperature range between 12 and 350 K. Our studies present unambiguous evidence for the presence of the ferroelectric

(R3c) phase (FE) of NaNbO3 coexisting with an antiferroelectric phase (Pbcm) over a wide range of temperatures. (S.K.

Mishra et al., (2007).

The physical properties in charge ordered manganites are influenced by magnetic

field, pressure, and substitution effects. Here we study the effect of change in

ionic radii on the magnetic structure and its influence on the measured physical

properties. The figure shows a section of the neutron diffraction pattern of

La0.5

Ca0.5-x

SrxMnO

3 at 15 K. With increase in Sr concentration the magnetic

structure evolves from a CE-type antiferromagnet to ferromagnet with an

intermediate A-type antiferromagnetic structure. The magnetic structure

influences the magnetic and transport properties .

Some references:

1. S.K. Mishra et al., Phys. Rev. B 76, 024110 (2007).

2. I. Dhiman et al., Solid State Communications 141, 160 (2007).

3. S. Taran et al., J. Phys. Cond. Matter (in press).

4. Brajendra Singh et al., J. Appl. Phys. 101, 09G518 (2007).

5. S. N. Achary et al., J. Alloys and Compounds 438, 274 (2007).

Structure of NaNbO3

913 K (PE)300 K (AFE) 12 K (FE)

. Evolution of magnetic structures in charge ordered manganites



Beam hole no. TT1015

Monochromator Bent perfect Si

Wavelength 1.48 Å(standard)

Beam size 15 × 25 mm2

Flux at sample 7×107 n/cm2/sec

Scattering angle 6 – 123O

Q range 0.4 – 7.4 Å-1

(1.48 Å)

Δd/d ~ 0.3%

Detector 4 Linear 3HePSDs (to beupgraded to12 nos.)


This diffractometer, installed recently,with focusing monochromator,is expected to be widely used in thearea of chemical and magnetic structuresof novel materials.

This powder diffractometer developed

and installed by UGC-DAE

Consortium for Scientific Research, is

a multi-PSD high throughput

diffractometer. It employs a bent

perfect crystal monochromator at a

take-off angle of 90

degrees and it is

designed for a

highly focused

neutron beam of

about 15 x 25 mm2

in size. This would

enable high flux

at sample position

and also use of

small samples

(~1 cc in volume).

The resolutions obtained are up to

Δd/d ~ 0.3%.

The monochromator can be rotated or

flipped to give a range of wavelengths

from 1.1 to 2.3 Å. The sample

environment consists of a 4 K CCR for

standard measurements as a function

of temperature and a cryogen-free

7 Tesla magnet with VTI for in-field

measurements down to 1.4 K. An

oscillating radial collimator (under

installation) will be used to suppress

extraneous contributions from the

magnet and CCR shrouds. The data

acquisition system, developed locally,

has an input for up to 16 PSDs and

the software enables recording various

sequences of measurements with

respect to incident neutron flux and

sample temperature.


. Monochromator Rocking Curve and Beam Profiles

Rocking curve of bent perfect Si monochromator at a take-off angle of 90º

and λ = 1.48 Å. Figures on right show the horizontal and vertical beamprofiles measured at sample position.

Some references:

1. A.V. Pimpale, B.A. Dasannacharya, V. Siruguri, P.D. Babu, P.S. Goyal, Nucl. Instrum. Meth.A481 (2002) 615

2. S. Patnaik et al (unpublished)

. Neutron diffraction pattern of YMnO3 taken at room temperature [2] at λ = 1.48 Å.



Beam hole No. T1009

Wavelength 1.201 Å

Beam polarization 98.83%

Flipper RF flipper /DC flipper

Flux at sample 3.6x105

n/cm2/sec


Analyzer efficiency 97.36% /99.89%

Detector BF3 counter

Available T range 1.5 – 300 K

Available H 1.2 kOe

The polarized neutron spectrometer (PNS) is used for magnetic

scattering studies. This spectrometer can be used in different

modes, such as (a) diffraction mode (2-axis configuration), (b)

polarization analysis mode (3–axis configuration in scattering

geometry), and depolarization mode (3-axis configuration in

transmission geometry). The instrument has been used for

studying mixed ferrites, 3d-based alloys, uranium / thorium /

cerium based intermetallic compounds, amorphous magnets,

CMR perovskites, quasi 1-D spin chain compounds, etc.

PolarizedNeutron

Spectrometer

This PNS instrument is installedat the end of the tangential beamhole No. T1009. The spectrometeris used for magnetic correlation studies.

S. M. Yusuf and L. Madhav Rao, Neutron News 8, 12 (1997).S. M. Yusuf and L. Madhav Rao, Pramana- J. Phys. 47, 171 (1996).


Selected examples

. Magnetic and Electronic Phase Transitions-Ionic Size Effect in (La1-x

Dyx)0.7

Ca0.3

MnO3

CMR Perovskites

Increasing Dy concentration drives the system first into a local cantedferromagnetic (LCF) state with a reduced metal-insulator transition temperature(for x = 0.114 and 0.243) and then (for x = 0.347) to an “insulating”cluster-spin glass state .

. Neutron Depolarization Study on CMR Perovskites (Nd1-x

Tbx)0.55

Sr0.45

MnO3

Some References:

1. S. M. Yusuf, L. Madhav Rao and P. Raj, Phys. Rev. B 53, 28 (1996).2. S. M. Yusuf et al., Solid State Commun. 112, 207 (1999).3. S. M. Yusuf, M. Sahana, K. Dorr, U.K. Röbler and K. H. Müller, Phys. Rev. B 66, 064414 (2002).4. S. M. Yusuf et al., Phys. Rev. B 68, 104421 (2003).5. S. M. Yusuf et al., J. Magn. Magn. Mater. 272-276, 1288 (2004).

The crossover from long-range to short-range magnetic ordering in the CMR perovskites is studied by complementaryneutron scattering techniques. A canted ferromagnetic state for x < 0.5 with large domains (> 1000 nm), ferromagnetic-like spin clusters of ~ 100 nm size for 0.5< x < 0.6 and only short range correlation of ~ 5 nm for x > 0.6 compositions havebeen observed.



Beam hole no. HS1019

Monochromator Cu (220): λ = 0.783ÅCu (111): λ = 1.278Å

Flux at sample 2x106 (λ = 1.278 Å(n/cm2/sec) 3x105 (λ = 0.783 Å)

Sample size 40 mm high &5-10 mm dia


Detector 10 (1-d PSDs)at 5 positions

Q range 0.3 – 15 Å-1

ΔQ/Q 2.5 %

Hi-Q diffractometer is a multi-

PSD based instrument covering

Q-range up to 15 Å-1. It has been used

for structural studies of a number of

molecular fluids, chalcogenide

glasses,borate glasses, phosphate

High - QDiffractrometer

This High-Q diffractometer is a conventionalneutron powder diffractometer with highQmax (=15 Å-1) with λ = 0.783 Å and isused mainly to understand short rangeorder in glasses, liquids and disorderedcrystals.

glasses, tellurite glasses, sulphide

glasses, amorphous carbon and also

in studies of local structure

determination from disordered

crystalline systems. This diffractometer

has also been used to study high

pressure structural phase transitions

in α-Resorcinol, NbO2F etc., using a

home made piston cylinder type

pressure cell using EN45 steel as the

cell material.


Selected examples

. H-bonded simple alcohols

Simple alcohols like CD3OD, t-butanol

and 2-propanol show intermediate

range order characterized by

a pre-peak which is due to molecular

clusters (mainly hexamer) through

H-bond association. On the other

hand 1-propanol does not show any

pre-peak and the H-bonded

association of the molecules lead to

open chain clusters instead of closed

cyclic chain clusters. The main reason

is that the first group of alcohols all

have methane like structure where as

1-propanol is a linear molecule. The

top right hand side figure shows

schematic of the cyclic chain clusters

. Rare earth phosphate glasses: Radioactive waste storage materials

T(r) shown for R=Ce glass showing

the P-O, R-O & O-O distances. PO4

tetrahedra are the basic building blocks in

these glasses

Glasses with general formula 0.1La2O

3 - 0.1R

2O

3 - 0.05Al

2O

3 – 0.75P

2O

5 are candidates of radioactive waste storage

materials as they are chemically durable and pouring temperatures are low. Some phosphate glasses have low leachingrates compared to the alternative borosilicate glasses. We found that these glasses have mainly PO

4 tetrahedral units. R-O

co-ordination is about 6 to 8. A 3D-hand built model is displayed with the intention of confirming the feasibility ofconstructing a continuous random network. Some of these glasses are found to be good candidates as UV filters anda patent has been obtained for the same.

Some References:

1. A.G. Shikerkar et al., J. Non-Cryst. Solids. 270, 234 (2000).2. A.K. Karmakar et al., Phys. Lett. A 253, 207 (1999).3. P.P. Nath et al., Z. naturforschungs 56a, 825 (2001).4. A. Sahoo et al., Pramana – J. Phys. 63, 183 (2004).5. Keka R. Chakraborty et al., Pramana – J. Phys. 63, 245 (2004).

n 2-propanol whereas the bottom one shows open chain clusters in 1-propanol.



Beam port Guide G1

λ* (guide cut-off) 2.2 Å

Monochromator BeO Filterat 77 K

λcut-off 4.7 Å

λaverage 5.2 Å

(Δλ/λ) ~15 %

Flux at sample 2.2×105 n/cm2/sec

Source slit (S1) 3 cm × 2 cm

Sample slit (S2) 1.5 cm × 1 cm

Distance S1 & S2 2 m

Angular divergence ± 0.5o

Detector (D) linear He3-PSD

Distance S2 & D 1.85 m

Q range 0.017 – 0.35 Å-1

The SANS diffractometer is widely

used to investigate the structure(shape and size) of different kinds of

mesoscopic systems such as micellarsolutions, magnetic fluids, protein

solutions and colloidal suspensions.

Small-angleNeutron

ScatteringDiffractometer

This SANS diffractometer isinstalled at the end of one ofthe guides. The diffractometeris suitable for studies ofinhomogeneities of the sizesin the range 10 – 200 Å.

This is a conventional slit-geometry SANS diffractometer. It makes use of BeOfilter as a monochrometer. The beam passes through two slits S1 and S2 before

it is incident on the sample. The angular distribution of neutrons scattered by thesample is recorded using a 1-m linear positive sensitive detector.

V.K. Aswal and P.S. Goyal, Current Science 79, 947 (2000)


Selected examples

. Protein crystallization in aqueous salt solutionThe process of proteincrystallization is of interestfrom both scientific andbiological aspects.Structural evolution amongprotein macromolecules isan important step inunderstanding the processthat the system isundergoing duringcrystallization. It has beenobserved that the effect ofsalt concentration as well

as that of different salts on protein crystallization is markedly different (Fig. 1). SANS data suggest that difference in thecrystallization on varying concentration/type of salt is related to the differences in structures in these samples in terms of thepopulations of monomers and dimmers (Fig. 2). Higher-mers are not observed as they are formed in very small numberstowards the process that leads to crystallization.

. Tuning gelation of block copolymer/surfactant mixed systemsS e l f - a s s e m b l ybehavior of theP E O - P P O - P E Obased triblockcopolymers havebeen studied quiteextensively in viewof their richs t r u c t u r a lp o l y m o r p h i s mand numerousapplications in theindustries. In manyapplications, they

are used in combinations with ionic surfactants like SDS, CTAB etc. Fig. 4 shows lower (T1) and upper (T2) meltingtemperature of cubic gels formed by 25% of block copolymer (EO)20(PO)70(EO)20 solutions as a function of SDS concentration.The gel phase can be tuned by the ratio of the two components. Contrast variation SANS studies show that the blockcopolymer and SDS form mixed micelles comprising a uniform distribution of the respective molecules (Fig. 4).

Some references

1. V.K. Aswal and P.S. Goyal, Phys. Rev. E 6161616161, 2947 (2000).2. J. Sharma, V.K. Aswal, P.S. Goyal and H. Bohidar, Macromolecules 3434343434, 5215 (2001).3. J. Haldar, V.K. Aswal, P.S. Goyal and S. Bhattacharya, Angew. Chem. Int. Ed. 4040404040, 1228 (2001).4. S. Chodankar and V.K. Aswal, , , , , Phys. Rev. E 7272727272, 041931 (2005).5. R. Ganguly et al., J. Phys. Chem. B 110110110110110, 9843 (2006).

Fig. 4Fig. 4Fig. 4Fig. 4Fig. 4Fig. 3Fig. 3Fig. 3Fig. 3Fig. 3

Fig. 1Fig. 1Fig. 1Fig. 1Fig. 1 Fig. 2Fig. 2Fig. 2Fig. 2Fig. 2



Beam port Guide G1

Monochromator Si(111)

Wavelength (λ) 3.12 Å

(Δλ/λ) ~1 %

Flux at sample 500 n/cm2/sec

Analyser Si(111)

Q range 0.0003-0.0173 Å-1

Real space 200 - 10000 Åresolution

Detector BF3 Counter

This facility is widely used toinvestigate the mesoscopicinhomogeneties in ceramics,metallurgical alloys, naturallyoccuring porous media like rock etc.

In this kind of double crystal basedinstruments, unlike pinholecollimation instruments, thecollimation is performed in thereciprocal space only and theresolution in wave vector transfer Q isindependent of the beam crosssection. Because of the non-dispersive setting of both the crystals,the width of the rocking curve isindependent of the divergenceof the incoming beam.

DoubleCrystal based

SANSInstrument

This is a double crystal based mediumresolution small-angle neutron scatteringinstrument built and commissioned at theguide tube laboratory. The instrumentconsists of a non-dispersive (1, -1) setting of(111) reflections of silicon single crystals withsample between the two crystals.

S. Mazumder, D. Sen, T. Saravanan and P. R.Vijayaraghavan,J. Neutron Research 9, 9, 9, 9, 9, 39 (2001)


Selected examples

. Effect of pore structure on low frequency dielectric response in ZrO2-8 %Y2O3 ceramic compact

Yttria stabilized zirconia is

a potential candidate forsolid oxide fuel cell

applications. SANS data forZrO2-8 % Y2O3 pellet

samples with identicalporosity but prepared from

finer and coarser grain areshown (left). Scattering

experiments have beencarried out for

two different samplethicknesses in order to

correct for multiple scattering. The real and the imaginary components of the dielectric response forthese samples are depicted (right). The variation in the dielectric response has been explained by a pore

structure dependent interfacial polarization, ion hopping and conduction.

. Carbide precipitates in solution quenched PH 13-8 Mo stainless steelPH13-8 Mo, because of itshigh strength andtoughness, coupled with

good corrosion resistance, isoften used in aircraft, nuclear

reactor, petrochemical plantsand many other challenging

applications. SANS data fromsolution quenched (from

1000oC) sample for twodifferent sample thickness

are shown (left). Theestimated single scattering profile is also shown in the inset. TEM (left inset) shows the presence block like precipitates. The

size distribution of the parallelepiped block precipitates, estimated from SANS, is shown (right).

Some references

1. D. Sen, S. Mazumder and S. Tarafdar; J. Mat. Sci 3737373737, 941 (2002).2. S. Mazumder et al. Phys. Rev. Lett. 9393939393, 255704 (2004); S. Mazumder, et al Phys. Rev. B 7272727272, 224208 (2005).3. D Sen, T. Mahata, A K Patra, S Mazumder and B P Sharma; J. Phys.: Condens. Matter 1616161616, 6229 (2004).4. D. Sen et al. Mat. Sci. & Eng A 397397397397397, 370 (2005); J. Mittra et al. Scripta Materilia 5151515151, 349 (2004).5. A.K. Patra, S. Nair, A.K. Tyagi, D. Sen, S. Mazumder, S. Ramanathan; J. Alloys and Comp. 403403403403403, 288 (2005).



Monochromator Si(113)

Wavelength 2.5 Å

ΔQ/Q 0.141 - 0.411

Polarizer FeCo/TiZrsupermirror


D.C. flipper 92 %efficiency

Detector linear He3 PSD

Reflectivity 1 – 10-4

The reflectometer uses a linear position sensitive detector, which helpsto collect the off-specular reflectivity data in addition to specular

reflectivity data from the thin film samples, in a single setting.

This facility has been widely used for structural and magneticcharacterization of thin film samples, using specular and off-specular

techniques.

Reflectivity is intrinsically sensitive to the difference of the refractiveindex (or contrast) across any interface. For the case of specular

reflection, the intensity of the reflected beam is related to the depthdependence of the index of refraction averaged over the lateral

dimensions of the sample. Polarized neutron reflectometry is a uniquetechnique to study the depth profile of magnetic moment in multilayer.

Off-specular or diffuse neutron reflectivity is a widely used techniqueto understand surface (interface) morphology.

PolarizedNeutron

Reflectometer

The polarized neutron reflectometeris located in Guide Tube laboratory.The reflectometer has been designed forvertical sample geometry. It utilizes ahighly collimated monochromatic:polarized or unpolarized beamof neutrons.

Saibal Basu and Surendra Singh, J. Neutron Research 1414141414, 109 (2006).


Selected examples

. Investigation of interface magnetic moment in Fe/Ge multilayer

Metal-semiconductor interfaces display transport and magnetic properties which strongly depend on interface quality viz.roughness, alloying at interfaces, and magnetic moment at interface. Polarized neutron reflectivity data on Fe/Ge multilayers(left and right) have been used to clearly demonstrate that there is overall reduction in magnetic moment of Fe atoms as wellas asymmetry of moments at the Fe/Ge interfaces.

. Corrosion-induced morphology in Ni Film: a study in off-specular reflectometry

The microscopic fractal morphology of corrosion front at the exposed air-film interface of a Ni film as well as the morphologyof an interface buried below the affected surface layer have been used to determine off-specular neutron reflectivity (right)and specular neutron reflectometry (left) in unpolarized mode. Differences in morphology, of a hidden interface vis-à-visthe exposed surface under corrosion (middle), at microscopic length-scales have been quantified in terms of fractaldimension of these two surfaces.

Some references

1. Surendra Singh, Saibal Basu, M. Vedpathak, R. H. Kodama, R. Chitra and Y. Goud, Appl. Surf. Sci. 240240240240240,251 (2005).

2. Surendra Singh, Saibal Basu, A.K. Poswal and M. Gupta, Solid State Comm. 136136136136136, 400 (2005).3. Surendra Singh and Saibal Basu, Surf. Sci. 600600600600600, 493 (2006).4. Surendra Singh, S.K. Ghosh, Saibal Basu, M. Gupta, P. Mishra and A.K. Grover, Electrochem. & Solid State Lett.

99999, J5 (2006).5. Surendra Singh, Saibal Basu, Mukul Gupta, Mahesh Vedpathak, and R.H. Kodama, J. Appl. Phys. 101101101101101,

33913 (2007).



Beam port Guide G2

λ∗ (guide cut-off) 3.1 Å

Monochromator BeO Filter (77 K)

λcut-off 4.7 Å

λaverage 5.2 Å

(Δλ/λ) ~15 %

Flux at sample ~105 n/cm2/sec

Detector (D) linear He3-PSD

Real space length 20-400 Åscale

Q range (SANS) 0.015 – 0.3 Å-1

Spin Echoand

Polarized SANSInstrument

This instrument consistsof two arms,i) Spin echo andii) polarised neutronssmall angle scattering.

The spin echo technique is used tostudy stochastic dynamics of polymers,

macromolecules etc. BeO filterproduces a quasi-monochromatic

neutron beam. A focusing soller-typemulti-segment supermirror based

polarizer and analyzer are used topolarize and analyze the neutrons.

Similar π and π/2 flippers are used tochange the direction of neutron

polarization. A multilayer copper wiresolenoid is used as guide field to

initiate Larmor precession of theneutrons. A 3He detector is used to

detect the neutrons. The maximumq-range is 1 Å-1. Dynamical systems

of real space correlations of about10 Å and a time scale of 1 ns can be

investigated.

The small angle scattering instrument is a slit geometry configuration, using BeO

filter cooled at liquid nitrogen temperature. The incident neutrons are polarizedusing a multi-segment soller type

supermirror polarizer (Co/Ti coatedwith anti-reflecting Gd coating). The

distance between the sample and thedetector is 2.21 m which may be

increased to about 3 m. This setup canbe used to investigate shape and size

of different mesoscopic systems likemicellar solutions, proteins and the

study of magnetic inhomogeneties.


Some references

1. S. L. Chaplot, R. Mittal, Prabhatasree Goel, Appl. Phys. A7474747474 (suppl). S280 (2002).2. S. L. Chaplot, R. Mittal, K. N. Prabhatasree, Neutron spin echo spectroscopy, eds. F. Mezei, C. Pappas and T.

Gutberlet (Springer verlag, Berlin 2003) p 48.

Selected examples

. Surfactants in aqueous solution

Surfactants are amphiphilic molecules with water repelling and water loving ends, they self-assemble to form micelles inaqueous solutions. SANS data on 0.2 M micellar solution of anionic surfactant Sodium Dodecyl Sulphate prepared in D2Oare shown. SANS distribution shows a correlation peak at Qmax ~ 0.07 Å

-1, which is due to a peak in the interparticlestructure factor S(Q). This corresponds to average distance (~2π/Qmax) between micelles of about 90 Å.

. Cobalt precipitates in Copper annealed at 560O CSmall angle neutronscattering studies on diluteCu alloy with 0.8 at %Co havebeen carried out. Cobalt formsprecipitates whose sizesdepend on reaction kinetics.The sample studied wassolution treated at 950OC for3 hrs in a vertical furnace inargon atmosphere, followedby rapid quench into waterat room temperature andannealed at 560OC for 80minutes.



Beam hole no. T1007

Monochromator Cu(111)

ΔE range 3 – 200 meV

Q range 1 – 10 Å-1

lncident 0.6 – 2.3 Åwavelength range


Analyzer PG(0002)

Filter PG

Scattering angle 10o – 100o


Triple AxisSpectrometer

This instrument is used tostudy inelastic Neutron Scatteringfrom single crystals andpolycrystalline samples.

This instrument has been successfullyemployed for measurement of phonondispersion curves, phonon density ofstates, crystal field excitations andquasielastic scattering.

The geometry of the triple axisspectrometer allows measurements ofthe scattering function S(Q,E) in singlecrystals at well defined values ofmomentum transfer Q and energytransfer E.

Principal components of thisinstrument are:

(i) Monochromator that producesthe mono-energetic neutronbeam.

(ii) Positional spectrometer that setsthe angles φ and ψ.

(iii) Analyzer that measures theoutgoing energy.

Various arms of the spectrometer canbe moved at angular speeds of severaldegrees/ minute by means of wormgear assemblies.

The shielding wedges of the monochromator shield are lifted automatically toallow for continuous variation of the monochromator settings.

S.L. Chaplot, R. Mukhopadhyay, P.R. Vijayaraghavan, A.S. Deshpande andK.R. Rao, Pramana - J. Phys. 3333333333, 595 (1989).


Selected examples. Al2SiO5: Andalusite, a polymorph having five-coordinated aluminiumAl2SiO5 exists in threepolymorphic forms: sillimanite,

andalusite and kyanite with onealuminium in tetrahedral, five-

coordination and octahedralcoordination respectively. These

display unique phase transitionswith pressure and temperature

and the phase diagram hasextensive applications in

geophysics. Experiments on allthree phases validated a

transferable interatomic potentialto explain vibrational and

thermodynamic properties of these polymorphs. (Left) Polyhedral representation of andalusite crystal structure with AlO6octahedra in red, five-coordinated Al in blue, SiO4 tetrahedra in yellow. (Right) Measured (solid squares) and calculated

(solid line) phonon dispersion curves along the Σ direction in andalusite. The (zone centre) phonon frequencies knownfrom Raman (open triangle) and infrared (open diamond) measurements are also shown.

. M2O (M=Cu, Ag): Negative Thermal Expansion materialsM2O (M=Cu, Ag)

exhibits negative thermalexpansion (NTE).

Experiments helped todevelop lattice dynamical

model which identifiedlibrational mode related

to NTE, explainedbond length variation

in agreement withpublished EXAFS data, and stabilized lattice with a single M-M potential. (left) Experimental and calculated phonon spectra

for Cu2O. (centre) Structure of M2O. The solid circles denote M and O atoms in decreasing order of size. (right) Polarizationvector of T2u mode shows rotation of M4O (M=Cu,Ag) tetrahedra about the aaaaa axis.

Some references

1. R. Mittal, S.L. Chaplot, S.K. Mishra, Preyoshi P. Bose, Phys. Rev. B75 (2007) 174303.2. A. Sen, Mala N. Rao, R. Mittal, and S.L. Chaplot, J. Phys.: Condens. Matter, 17 (2005) 6179.3. R. Mukhopadhyay, A. Sayeed, Mala N. Rao, A.V. Anilkumar, S. Mitra, S. Yashonath, S.L. Chaplot, Chem.Phys.

292 (2003) 217.4. R. Mittal, S.L. Chaplot, A. Sen, S.N. Achary, A.K. Tyagi, Phys. Rev. B 67 (2003) 134303.5. P. Goel, Mala N. Rao, N. Choudhury, S.L. Chaplot, Subrata Ghose, M. Yethiraj, Appl. Phys. A 74 [Suppl.]

S1149 (2002).



Beam hole no. TT1004

Monochromator (2 nos. in tandem)crystals (2nd one vertically focused): PG(0002) (100 × 80 mm2)

λincident 1.3 – 4.7Å

Scattering angle 2θ< 80O

Flux at sample 5 ×105 n/cm2/sec

Analyser PG(0002)(MARX Mode)

ΔE range 2.3 meV(for Ei=4 meV)

ΔE/E 4 %

QuasiElastic Neutron

Scatteringinstrument

This instrument is used to studyStochastic Motion (like Diffusion) inCondensed Matter. ‘Quasi’ means nearelastic (≤ 2 meV). Provides informationabout the time scale and geometry ofdiffusive motion as also the potentialexperienced by the species.

Some distinct features of thisinstrument are mentioned below:

• Virtue of Double Monochromator,neutrons of different incident

energy can be obtained at a fixedsample position

• The instrument works in Multi

angle Reflecting X-tal mode (MARX)thereby facilitating complete energy

spectrum for one instrumentalconfiguration.

• Provision to change in the distance

between different axes to obtaindifferent energy resolutions.

• The out-of-pile portion of the

instrument is on a ‘tanzboden’facilitating easy maneuvering

R. Mukhopadhyay et al. , Nucl. Instr. Meth. A 474 474 474 474 474, 55 (2001).S. Mitra and R. Mukhopadhyay, Current Science 8484848484, 653 (2003)


Selected examples. Alkyl Chain Dynamics in Monolayer Protected Metal nano-Clusters (MPCs)

Schematic of MPCs system

A) Isolated MPCs (Au-clusters): Chains are dynamic only above Tc (340 K: chain melting) and all the chains are dynamic.B) Superlattice MPC (Ag-clusters): Only chains (50 %) are dynamic < Tc (393 K: Superlattice melting) Others held due to

interdigitation . T> Tc all the chains dynamics.

. Diffusion of Molecular absorbed in Zeolite

MD Simulation results show translational motion exists in three differenttime scales. Only one contributes to QENS-data (Red circle). Rotational motion

is much faster and measurable in Triple axis spectrometer with a wider energywindow.

Rotational Diffusion coefficient

of propane in Na-Y zeolite

Some references

1. T. Pradeep, S. Mitra, A. Sreekumaran Nair, R. Mukhopadhyay, J. Phys. Chem. B 108108108108108, 7012 (2004).2. A. Sayeed, S. Mitra, A. V. Anil Kumar, R. Mukhopadhyay, S. Yashonath, S. L. Chaplot, J. Phys. Chem. B 107107107107107,

527 (2003).3. R. Mukhopadhyay, A. Sayeed, S. Mitra, A. V. Anil Kumar, Mala N. Rao, S. L. Chaplot, S. Yashonath Phys.

Rev. E 6666666666, 061201 (2002).4. Siddharth Gautam, S. Mitra, R..Mukhopadhyay, S. L. Chaplot, Phys. Rev. E 7474747474, 041202 (2006).5. S. Mitra, R. Mukhopadhyay, A. K. Tripathi, N. M. Gupta, Applied Physics A 7474747474, S1308 (2002).



Beam hole no. HS1017

Monochromator Doubly focusingCu(111)

ΔE range 15 – 250 meV

Q range 1 – 10 Å-1

Incidentwavelength range 0.6 – 2.3 Å


Analyzer Be filter

Scattering angle 10O – 100O


FilterDetector

Spectrometer

This instrument is usedto study inelastic neutron scatteringfrom condensed matter.

Principal components of thisinstrument are:

(i) Monochromator that producesthe mono-energetic neutronbeam

(ii) positional spectrometer that setsthe scattering angle.

(iii) Analyzer that measures theoutgoing energy.

Continuous variation of the incidentneutron energy is allowed for by liftingof the shielding wedges of themonochromator shield.

The scattered neutron beam from thesample is filtered by polycrystalline Bemade of beryllium blocks interleavedwith cadmium, intended to capture anyBragg diffracted neutrons. Theneutron scattering cross section of Beexhibits a sharp drop at a neutronenergy of 5 meV. Thus, neutronswhose energy is less than 5 meV areallowed to pass through the filter andall others are scattered out of thebeam.

C.L. Thaper, B.A. Dasannacharya,, and P.K. Iyengar, Nucl. Instr. Meth. 113(1973) 15.


Selected examples. Libration of NH4+ ion in NH4Cl at RT (CsCl Phase)Ammonium chloride NH4Cl is a simple ionic crystal containing distinctNH4

+ tetrahedra. At atmospheric pressure, three phases of ammonium chloridehave been found to exist. Above 243 K (i.e. in the CsCl (disordered) phase), theNH4

+ ions are randomly distributed between two possible orientations,with N-H bonds lying along threefold axes (body diagonals). Ammonium ions inthis room temperature phase may be considered torsional oscillators withfrequency ~ 359 cm-1 (~45 meV). This libration mode exhibits a ratherflat dispersion in the Brillouin zone, with the next branch occurring at least15 meV away.

. Vibration of Hydrogen in Zirconium Hydride (ZrH2)The thermal vibration spectrum ofzirconium hydride includes (in additionto the band of acoustical frequencies)a sharp “optical” frequency νcorresponding approximately tovibrations of the individual hydrogenatoms in an isotropic harmonic well.This implies a set of optical energylevels for the lattice En=nhν. Peakscorresponding to transitions betweenthese optical energy levels will be seenin the spectrum of neutrons scatteredfrom zirconium hydride. The firsttransition is observed as a peak at anenergy transfer of about 140 meV.

The data shown on this page have been taken on an instrument with a PG (0002) monochromator.



Beam hole No. 6 of Apsara,a swimming pool type Reactor

Useful beam size: 15 cm dia.

Thermal NeutronFlux: (n/cm2/sec) 1 x 106

Gamma level: 4R/h

Cadmium ratio: 6.3

Neutron/gammaratio: (n/cm2/mR) 9 x 105

NR Techniques used:converter screens : Gd (25 μm), Dy(100 μm), CCD- based imagingsetup, Neutron Imaging plate

NeutronRadiography

Applications

Non-Destructive Testing andEvaluation of :Nuclear fuel pins,fuel plates,ControlRods, INSAT-pyrovalves & cable cutters,electric detonator, marker shells, boralcomposites

Hydride blisters in zircaloy-2 and Zr-2.5%Nb PT coupons (lab generatedand from power reactor).

Hydrogen Sensitive EpithermalNeutron Radiography

Real time imaging, Two-phase flowstudy, Neutron tomography.

NR Facility At Beam Hole No. 6, Apsara reactor.

Schematic (above) Photograph of the Facility (below).

NR Album : Neutron radiographs of various objectsrecorded using film techniques

(1) INSAT Cable cutters

(2) INSAT Pyro valve(3) Fuel pins

(4) Flower plant through lead brick(1) (2) (3) (4)

←←←←←


Selected examples. Study of zirconium Hydride blister formation in zirconium based PHWR pressuretube materials.

A zirconium hydride blister of nearly 0.35% of job thickness could be detected using neutron radiography.

(1) (2)Hydride blisters in zircaloy-2

(1) and Zr-2.5%Nb(2) PT coupons

(Lab.generated)

Zr-Nb(R) PT coupon from a powerreactor. Enlarged view of the

blister shown at RHS

Neutron radiograph of burst tested Zr-2.5%Nb pressure tube piece containing

laboratory generated hydride blisters(B).The axial crack is seen passing through two

blisters at position 4 on the tube.

. Hydrogen SensitiveEpithermal Neutron(HYSEN) radiographytechnique

. CCD based Electronic imaging

HYSEN radiograph of 1-, 2-, 3-, 4- layers of cellophane adhesive tape as object.Calculated hydrogen sensitivity: 0.1 mg/cm2.

Neutron images of (1) carburetor, (2) spark plug, (3) INSAT cable cutter &

U-tube filled with wax recorded using electronic imaging system.

Some references

1. A.M. Shaikh, P.R. Vaidya, B.K. Shah, S. Gangotra and K.C. Sahoo, J. Non Destr Test. & Eval. 22222(3), 9-12, 2003.2. A.M. Shaikh, Suparna Bannerji and D.N. Sah The e-Journal & Exhibition of nondestructive

Testing-ISSN1435-4934, URL:www.ndt.net/article/nde-india2006/files/tp- 58-pap.pdf3. Amar Sinha, A.M. Shaikh, A. Shyam , Nucl. Instr and Meth. in Phys. Res. B 142142142142142, 425- 431, 1998.

(1) (2) (3)

1 2 3 4 ←←←←←


A large variety of neutron detectors both BF3 and 3He gas–filled and X-ray detectors with excellent characteristics and long

shelf life are routinely fabricated. They range from

. Small beam monitors (0.2c/nv) to. Large size signal detectors (200c/nv),. Single wire & multiwire 1-D position sensitive detectors (1-D PSDs). A curvilinear multiwire 1-D PSD and. A large area multiwire 2-D PSD.Typical energy resolution of these detectors is 8 % 25 % (FWHM) for BF3 and 5%-15% for

3He-filled detectors.

The detectors developed are of various dimensions, sensitivity and efficiency as per requirements,

Applications: Neutron scattering, flux monitoring, area monitoring and nuclear waste monitoring.

Developmentof NeutronDetectors

Fig.1. Various types of neutron andFig.1. Various types of neutron andFig.1. Various types of neutron andFig.1. Various types of neutron andFig.1. Various types of neutron andXXXXX-ray detectors developed by Solid-ray detectors developed by Solid-ray detectors developed by Solid-ray detectors developed by Solid-ray detectors developed by SolidState Physics DivisionState Physics DivisionState Physics DivisionState Physics DivisionState Physics Division

AAAAA : 2-D Position Sensitive NeutronDetector,

BBBBB : 1-D Position Sensitive NeutronDetectors,

C C C C C : Neutron Proportional Counters,

DDDDD : 1-D Curvilinear Position SensitiveNeutron Detector

EEEEE : 2-D Position Sensitive X-raydetector,

F:F:F:F:F: Microstrip Detector for X-rays andNeutrons,

G G G G G : X-ray Proportional counters,

HHHHH : 1-D Position Sensitive X-rayDetector.


. 3He-filled 1-D position sensitive neutron detector

Fig. 2. Picture of some of the high resolution 1-D PSDs developed.36DHP1 : 3He + Kr (8 + 4 bar), sensitive length 89 cm.

36CHP1 : 3He + iso-C4H10 (8 + 2 bar), sensitive length 89 cm.36CHP2 : 3He + Kr (10 + 4 bar), sensitive length 89 cm.

8E : 3He + Kr (3 + 1.5 bar), Anode: CCQF, sensitive length 17 cmPosition resolution: 4 mm – 7 mm, Efficiency: 60 % to 90 %

Fig.3. Neutron diffraction patterns of Nickel with

36DN2 and 36DHP1 obtained at high-Qdiffractometer at Dhruva (λ=0.783 Å.).

Sensitive area of 345 mm x 345 mm,pixel size: 5mm x 5mm and efficiency

of 70% for 4 Å neutrons has beendeveloped.

Fig. 4. Schematic of 2-D PSD for neutrons. The PSD is shown in photograph

(Fig.1.) as Å

Fig. 5. Position spectrum of 1″ φ directneutron beam (λ ≥ 4Å) (LHS) and thatof scattered beam with alumina sampleplaced in direct beam (RHS). Sample

to detector distance ∼1.5m.

. 3He-filled 2-D multiwire position sensitive neutron detector:


. 3He-filled 1-D PSD based on microstrip geometry:with anode : 12 μm, cathode:300 μm, pitch : 612 μm and active area of 20 mm x 15 mm is developedand tested for Neutron and X-rays.

Fig. 6. Schematic of designed microstrip pattern on insulating substrate(LHS)

A, anode; C, cathode; B, bonding pad; R,meandering resistive strip Photograph(RHS) of rectangular chamber containing the Microstrip plate (top plate not

shown),

Fig.7. Response of microstrip detector

to 1.5mm wide, , , , , 4Å neutron beam.Position resolution ~ 1.8 mm

. Neutron Detector Development and Testing Facilities:

Fig.8. Facility for Testing 1-D Position Sensitive Neutron Detector at Beam Hole

No. 9, Apsara. Schematic of Neutron Beam Collimator and Detector Shielding,Experimental Setup (left). The BF3-gas generation, purification and fillingBF3-gas generation, purification and fillingBF3-gas generation, purification and fillingBF3-gas generation, purification and fillingBF3-gas generation, purification and filling

stationstationstationstationstation is shown above.

Design of neutron detectors,Assembly of detector components,anode assemblyEvacuation and gas filling systems,Facility for performance Testing ofdetectors with laboratory andreactor sources

Some references

1. S. S. Desai and A.M. Shaikh, Rev. Sci. Instr. 7878787878, 023304 (2007).2. S.S. Desai and A.M. Shaikh, Nucl. Instr. and Meth. in Phy. Res. A 557557557557557,

607 (2006).3. S.S. Desai and A.M. Shaikh, J. of Neutron Research 1414141414, 121 (2006).4. A.M. Shaikh, S.S. Desai and A.K. Patra, Pramana: J. of Phys. 6363636363, 465

(2004).5. V.Radhakrishna, S.S. Desai, A.M. Shaikh and K. Rajanna, Curr. Sci. 8484848484,

1327 (2003).


Sample Environment Facilities

Low Temperature: CCR- 1.5 - 300 K

High Temperature: Furnace: 300-1800 K

High Pressure Apparatus: A piston-cylinder type high-pressure cell with pressure range up to 25 kbar.

Magnetic Field: 12 kOe at Room Temperature

1.5 kOe and 2 kOe in vertical and horizontal direction with CCR

Up to 7 Tesla and T=1.5 to 300 K


Contact Scientists


For further information about facilities and proposals for experiments contact:

Dr. S.L. Chaplot

Head, Solid State Physics Division

Bhabha Atomic Research Centre, Trombay

Mumbai 400085, India

Telephone: +91 22 25595376, 25593754

Fax: +91 22 25505151, 25519613

E-mail: [email protected]

Published by:

DrDrDrDrDr. Vijai K. Vijai K. Vijai K. Vijai K. Vijai Kumarumarumarumarumar,,,,,

Associate Director, Knowledge Management Group &

Head, Scientific Information Resource Division,

Bhabha Atomic Research Centre,

Trombay, Mumbai 400 085, India

[email protected]

Front PageC o n t e n t sNational Facility for Neutron Beam ResearchNeutrons for Condensed Matter ResearchSingle Crystal Neutron DiffractometerPowder Diffractometer-1Powder Diffractometer-2Powder Diffractometer-3Polarized Neutron SpectrometerHigh - Q DiffractrometerSmall-angle Neutron Scattering DiffractometerDouble Crystal based SANS InstrumentPolarized Neutron ReflectometerSpin Echoand Polarized SANSInstrumentTriple Axis SpectrometerQuasi Elastic NeutronScattering instrumentFilter Detector SpectrometerNeutron RadiographyDevelopmentof Neutron DetectorsSample Environment FacilitiesContact ScientistsFor further information about facilities and proposals for experiments contactBack Page

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National Facility for Neutron Beam Research [NFNBR]14.139.62.172/mumbai/nfnbr-book-R.pdfBhabha Atomic Research Centre, Mumbai, India 1 National Facility for Neutron Beam Research 2