Recent Results from INGA RUDRAJYOTI PALIT

Dept. of NUCLEAR AND ATOMIC Physics

TIFR

Outline: New features of the array at TIFR Recent results

Future possibilities

INGA campaigns at different accelerator facilities

INGA01 INGA03 INGA05 sINGA07-8 INGA08-9 INGA11-12

TIFR NSC VECC TIFR IUAC TIFR

DDAQ with INGA

Detector Array DSP DAQ

Host PC

PC for Storage & Analysis

• Mounting position for 24 Clovers (εP ~5% )

• 3 at 23o, 40o, 65o, 115o, 140o, 157o and 6 at 90o

• Detectors -> DSP cards -> PCI Bridge -> PC-> Gigabit -> PC

DSP based DAQ for 24 CS-Clovers and Ancillary detectors at TIFR

Technical specifications100 MHz & 12-bit ADC‘sData rate: 80 MB/secParticle ID in CsI detectors using digital pulse shapingTrigger less systemXIA based systemH. Tan et l., NSS 08, IEEE (2008) p 3196

Implementation for INGAModular so easily expandableVersatile with complex triggerHigh count rateHigh stabilityZero dead-timeLong lived isomer measurements R. Palit AIP Conf Proc. 1336 (2011) 573

R. Palit, et al. NIMA 680 (2012) 90

Angular Distribution & Polarization

Singles measurement with 60crystals each counting at 4- 5 kHzTotal throughput is 260 kHzData rate: 15 MB/secTrigger less modeCross section measurement

89Nb

DDAQ has Increased the data throughput by 10 times for INGADDAQ has Increased the data throughput by 10 times for INGA

Long Lived Isomers near N=50

A. Chakrabarti, et al. PRC 72, 054309 (2005)

Reconfirmed theprevious reportedT1/2 = 460 (10) nsec

R. Palit, et al,

T-stamped data

28Si + 65Cu @105 MeV

Indian National Gamma detector Array for high resolution spectroscopy of atomic

nuclei

How does simple pattern emerge in excitation of complex nuclei?

What are the different patterns possible?How are they related with symmetry and

correlations present in nuclei?What are the limits when the ordered pattern

will disappear?

High spin states near High spin states near shell-inversionshell-inversion

•18O + 18O•Super-deformationSuper-deformation

sd-shell

•Exotic rotations Exotic rotations •Symmetry Symmetry

A~110,130

Structure of heavy nucleiStructure of heavy nuclei•Octupole correlations•Effect of shape driving orbitals

A~200-240

Isomers near shell closureHigh-K isomersIsomers for application

Fusion of weakly bound nucleiFusion of weakly bound nucleiFission dynamicsFission dynamics

Physics Focus of INGA

Anti-magnetic rotation in 105CdD. Choudhury, et al. PRC82(2010)

Axial asymmetry In Cs isotopesAxial asymmetry In Cs isotopesH. Pai, et al PRC 84 (2011) H. Pai, et al PRC 84 (2011)

Recent results from INGA

Search for multiple chiral bandsSearch for multiple chiral bandsT. Trivedi, et al PRC 85 (2012)T. Trivedi, et al PRC 85 (2012)

Electric and Magnetic Rotations

Magnetic RotationObserved in 78 nuclei: Role of deformation and beyond MR

A~80

A~110

A~130

A~190

Level scheme

High spin structure of 112In

268 272 276

Cou

nts

3000

6000

9000

272 276 280

1500

3000

4500273 keV 320 273 keV1480

385 392 399

1500

3000

4500

385 392 399

800

1600

2400

544 552 560 568

500

1000

1500

Eγ [keV]

544 552 560 568

250

500

750

393 keV 3201480 393 keV

554 keV 320554 keV1480

Lifetime measurement for dipole band in 112In

Doppler Shift Attenuation study for sub-pico sec T1/2 levels decaying by 272, 393, 554, and 708 keV transitions

Comparison of B(M1) values with TAC calculations

1. Regular sequences of M1 transitionsRegular sequences of M1 transitions2. Weak or absent E2 transitionsWeak or absent E2 transitions3. B(M1) decreases with angular momentumB(M1) decreases with angular momentum

ε2 = 0.12 and γ = 60

ε2 = 0.08 and γ = 50

TAC configuration πg9/2 - ν((h11/2)2d5/2/g7/2)

T. Trivedi, et al., PRC85 (2012)

Magnetic & Antimagnetic Rotation

Ferromagnet Anti-Ferromagnet

Magnetic rotor Antimagnetic rotorRotational bands with ∆I = 1Near spherical nucleiWeak E2Strong M1B(M1) decreasing with freqShears mechanism

Rotational bands with ∆I=2Near spherical nucleiWeak E2No M1B(E2) decreasing with spinTwo-shears mechanism

S. Frauendorf Rev. Mod Phys 73, 463(2001)

Anti Magnetic Rotation in 105Cd

1st evidence of AMR to be operative in an odd-A nucleus

2 27/2 11/2 9/2( ) ( )g h gν π −ￄConf.:

θπ

42 sin)(32

15)2( effeQEB =SCM:

D. Choudhury, et al. PRC82, 061308 (R)(2010)

Microscopic Description of Anti Magnetic Rotation in 105Cd

D. Choudhury, et al. PRC82, 061308 (R)(2010)Zhao, et al., PRL 107, 122501 (2011)

First evidence of 2 AMR bands in one nucleus.

2 27/2 11/2 9/2( ) ( )g h gν π −ￄConf.:

AMR in 107Cd

Present work

Level scheme of 122I

Eexc =11.4 MeV

Spin = 30 ћ

Imax

P. Singh et al., Phys. Rev. C 85, 054311 (2012)20

Core excitations beyond maximally aligned configurations in 122I

Core-excitations

Aligned and anti-aligned states

Proton (Z=53)

Neutrons (N=69)Neutrons (maximally-aligned configuration)

Neutrons (anti-aligned configuration)

Imax=29+,29-

Imax=22+,21-

P. Singh et al., Phys. Rev. C 85, 054311 (2012)21

Detailed Spectroscopy of 112In & 108Ag isotopes using INGA

Meng et. al. PRC73 037303 (2006)

Odd-odd Isotopes near A ~ 110

Exotic 3-dim Rotation of Nuclei

S. Frauendorf, J. Meng NPA617, 131 (1997)Y. Shimizu, et al. PRC 72, 014306 (2005)

Chiral Rotation

+1

-1

-1

+1

+1

+1

+1

-1

-1

-1

I+4

I+3

I+2

I+1

I

Degenerate dipole bands of 108Ag

11B + 100Mo @ 39 MeVπg9/2⊗νh11/2 Two degenerate dipole bands have been identified

with linking M1 and E2 transitions

Projected Shell Model Calculation

Degenerate bands reproduced with triaxial deformationsε2=0.19 ε'= 0.135

G. Bhatt, J.A. Sheikh, R. Palit PLB 707, 237 (2012)

J. Sethi, R. Palit, et al.Preliminary data

High spin states of nuclei near N=50

Positive & negative parity bandsup to high spin using polarizationmeasurements.Negative parity high spin states using proton excitations p3/2 & f5/2 to g9/2

Thin target data to look for higherspin states

S. Saha, R. Palit, et al. PRC 86 034315 (2012).

Emergence of collectivity at high spin

in spherical nuclei

1f5/2

2p3/2

2p1/2

1g9/2

1g9/2

2p1/2

2p3/2

1f5/2

2d3/2

3s1/2

1g7/2

1d5/2

Z=40N=50

XX X

XX

Emergence of collectivity at high spin

in spherical nuclei

CNS Calculations

Some of the key future experimentswith particle gamma coincidence

• Identify candidates for prompt proton emission outside of Z~28, N~28

– Possibly neutron-deficient Te isotopes?

• Study astrophysically important nuclei around N=Z line

• Heavy nuclei spectroscopy with tagging on fast particle emission

• Investigation of proton rich nuclei in light mass region

• Investigation of lifetime of states in quasi-continuum

1

New features of INGA coupled to a DDAQ (incresaed data throughput (~10 times) compared to our previous analogue readout scheme)

Results of search for chiral bands in 108Ag & 112InAnti-magnetic rotation in 105,107CdRegular structure at high spin in spherical nucleus 89ZrCore excitations in 122I

Addition of ancillary detectors, HYRA spectrometer at IUAC and over all efficiency will enhance its capability for the investigation ofNuclear structure with varying J & T(N-Z) for probing

Different phases, their coexistence & transitions Insight for shell structure and residual interactions

Summary

Collaboration & Acknowledgements

S. Saha, J. Sethi, T. Trivedi, S. Biswas,

B.S. Naidu, P.B. Chavan, S. Jadhav, R. Donthi

D. Choudhury, S. Sharma ,Z. Naik, P. Singh, A.Y. Deo, H. Pai, S. Kumar, G. Mukherjee, S.Sihotra,

D. Mehta, A.K. Jain

P.K. Joshi, P. Verma, S. Sinha

And INGA Collaboration

H.C.Jain, R.K. Bhowmik, S. Bhattacharya, S.Kailas, A.K. Jain, A.K. Sinha, S.K. Basu,S. Muralithar, A. Goswami,, S. Bhattacharyya, S. Ghugre, D.C. Biswas, A. Chatterjee

R.G. Pillay, V. Nanal, I. MazumdarS.K. Sarkar

Pelletron-Linac staff members, Central Workshop & LTF of TIFR

Nilsson LevelsNilsson Levels

Single particle levels near Z ~114 N~164 shell gaps influence the structure of rotational bands for lighter nuclei

Structure of 234U with ICF

Experimental Condition:

52 MeV 9Be beam

1 mg/cm2 self supporting 232Th target

4 x 10^6 a-g-g coincidence

6 CS-HPGe (25%)

Coincidence with CPD array

ICF ER: 10 mb

ER: ~ 5 mb

G. J. Lane et al. page 304, NS98

Study of Octupole correlations in Np isotopesStudy of Octupole correlations in Np isotopes

In U-Pu-Cm region, the pairs j15/2

⊗g9/2 neutrons and i13/2 ⊗ f7/2 protons are at the Fermi surface

Octupole Correlations are strongest when the pair of orbits with ∆j=∆ℓ=3 are near the Fermi Surface

Strong octupole correlations are observed for the nuclei 238-244Pu

Would like to populate 235Np using 7Li(232Th,xn) reaction at 50 MeV

Future experiments with INGA coupled to ancillary detectors and Spectrometer

• Structure of high spin isomers• Structure of heavy nuclei with A > 200• Heavy nuclei spectroscopy with tagging on fast particle

emission• Identify candidates for prompt proton emission outside

of Z~28, N~28– Possibly neutron-deficient Te isotopes?

• Study of important nuclei around N=Z line• Investigation of proton rich nuclei in light mass region• Investigation of quasi-continuum to look for nuclear

shape evolution and dynamics1

Schematic drawing of HYRA at IUAC

N. Madhavan et al., Pramana75, 317 (2010)

Dual mode of Operation of HYRA at IUAC

Vacuum Mode:

● For A< 100 amu

● Inverse Kinematics

● Good beam rejection (two stage filter)

● Good Collection Efficiency (kinematics)

● Z, A identification using X, ∆E, E and T

Gas-Filled Mode:

● For A > 200 amu

● Normal Kinematics

● Good beam rejection (charge equilibrium)

● Good Collection Efficiency (q, v focus)

Z, A identification using recoil decay tagging

High spin states of nuclei near N=50

13C + 80Se @ 60 MeV; Thin target

Sum of double gates89Zr

Sudipta Saha, R. Palit, et al. (PRC 86 (2012).

High spin states in 89Zr

33/2

A regular sequence of ∆I = 1 magnetic transitions

Spin range: (33/2+ up to 49/2+)

ħ2/2I ~ 14 keV

M.I. Similar to 93Nb and 131La

No cross-over E2 (high K)

Need to wait for getting confirmation for precession mode as predicted near shell closure

What is expected for chiral scenario (general)

Chiral vibration near the band head (I <Ic)

Near degeneracy at sufficient spin (chiral tunneling induces energy separation) (I>Ic)

Small inter band E2 transitions (I>Ic)

Identical band properties ShapeMoment of inertia Identical/similar intra band B(M1) & B(E2)

Spin independence of S(I) =[E(I)-E(I-1)]/2I: small Coriolis and deformation aligned geometry with a triaxial core (all I)

R. Palit, NN2012, 27 May - 1 June 2012

Most consistent with chiral interpretation: 135Nd

S. Zhu et al., PRL91 132501, 2003S. Zhu et al., PRL91 132501, 2003

110110Pd (Pd (3030Si, 5n)Si, 5n)0.5mg/cm0.5mg/cm2 2 X 2 X 2 Gam.Sph.(LBNL)Gam.Sph.(LBNL)γγγγγγγγ <= trigger<= trigger

πh11/22νh11/2

νh11/2

S(I)=[E(I)-E(I-1)]/2I

0

5

10

15

20

25

30

8 12 16 20 24 28 32 36 40 44 48

2I

S(I)

Band A

Band B

E(I)A-E(I)B

-50

0

50

100

150

200

250

300

350

27 29 31 33 35 37 39 412I

E(I) A

-E(I)

B (k

eV)

Cryostat modules housing the resonators with liquid He distribution box

Critical components of LINAC are designed, developed and fabricated indigenously

Heavy Ion Accelerator

R.G. Pillay et al.

Basic Configuration at TIFR from 2010

• Set up in Beam hall II of TIFR-BARC (LINAC beam hall)

• Mounting position for 24 Clovers (~5% εP )

• Movement on rails for precision alignment

• Space for mounting Charged Particle Array• 3 at 23o, 40o, 65o, 115o, 140o, 157o and 6 at 90o

Basic characteristics of DDAQ

dtredttI rt−=)(1

peak/total BGO off BGO on

Single crystal ~ 10% ~ 15 %

Clover Add-back ~ 22% ~ 40%

Neutron Multiplicity Filter

R.Palit, et al, NIM 443, 386 (2000)

Neutron Multiplicity Filter

AMR in 105Cd

1st evidence of AMR to be operative in an odd-A nucleus

2 27/2 11/2 9/2( ) ( )g h gν π −ￄConf.:

θπ

42 sin)(32

15)2( effeQEB =SCM:

A.J. Simons, PRC 72, 024318 (2005)

Timing with Fast Scintillators LaBr3(Ce)

LaBr3(Ce) Source LaBr3(Ce)

α gated γ spectra : t + 198Pt : 201Au* (ERs 198Au, 199Au)

t gated γ spectra : α + 198Pt : 202Hg* (ERs 200Hg, 199Hg)

A. Srivastava, et al.

Particle-gamma Coincidence

Reduced transition probability B(M1) values decreases rapidly with increasing spin, showing the shears mechanism.Experimental values are in good agreement with TAC calculations.Weakly deformed axially symmetric structure contrary to the perdition of RMF calculations which indicates multiple chiral bands on triaxial deformation.A pair of degenerate dipole bands have been identified in 108Ag.TPSM calculations reproduce the degenerate bands.Need to do lifetime measurements to confirm the predictions of RMF calculations.

Summary for 112In & 108Ag

1446

108Ag

155 – 403 – 346 – 502 – 393-341 - 310

High spin states of nuclei near N=50 Motivation:Shape isomers in high spin states near shell closure

Odahara et al Jour. Soc J77 (2008)

Precession mode predictedShimuzu et al. PRC72 (2005)

Wakabayashi et al Jour. Soc. J76 (2007)

High spin Isomers with two LaBr3(Ce) coupled to INGA

1944

270

270

1944

89Zr: 1944 – 780 – 270 – 1740 cascade extending the level scheme to 25/2+

270 – 1740 keV

Sudipta et al.

LaBr3

Clover