Tracking saddle-to-scission dynamics using N/Z in projectile

breakup reactions

SYLVIE HUDANApril 1, 2012

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Dynamical Breakup

Montoya et al., PRL73, 3070 (1994); Bocage et al., NPA676, 391 (2000)

Davin et al., PRC65, 064614 (2002); Colin et al., PRC67, 064603 (2003)

McIntosh et al., PRC81, 034603 (2010)

From Colin et al.

Observation of strongly aligned decay in mid-peripheral collisions at intermediate energies with:

Large yieldLarge relative velocity relative to fission

S. Hudan et al., PRC71, 05402 (2006)

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Dynamical Breakup

➡ Transiently deformed nuclei➡ Early cluster production

Montoya et al., PRL73, 3070 (1994); Bocage et al., NPA676, 391 (2000)

Davin et al., PRC65, 064614 (2002); Colin et al., PRC67, 064603 (2003)

McIntosh et al., PRC81, 034603 (2010)

From Colin et al.

Observation of strongly aligned decay in mid-peripheral collisions at intermediate energies with:

Large yieldLarge relative velocity relative to fission

S. Hudan et al., PRC71, 05402 (2006)

AMD

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Dynamical Breakup

➡ Transiently deformed nuclei➡ Early cluster production

Montoya et al., PRL73, 3070 (1994); Bocage et al., NPA676, 391 (2000)

Davin et al., PRC65, 064614 (2002); Colin et al., PRC67, 064603 (2003)

McIntosh et al., PRC81, 034603 (2010)

From Colin et al.

Observation of strongly aligned decay in mid-peripheral collisions at intermediate energies with:

Large yieldLarge relative velocity relative to fission

S. Hudan et al., PRC71, 05402 (2006)

AMD

What is the isotopic composition of those fragments?

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Experimental Setup124Xe 124Sn 112Sn1.30 1.48 1.24

FIRST: T. Paduszynski et al., NIMA 547, 464 (2005)

124(,136)Xe + 112, 124Sn @ 49.2 MeV/AExperiment performed at GANIL (France)

N/Z

BEAM

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Experimental Setup124Xe 124Sn 112Sn1.30 1.48 1.24

FIRST: T. Paduszynski et al., NIMA 547, 464 (2005)

124(,136)Xe + 112, 124Sn @ 49.2 MeV/AExperiment performed at GANIL (France)

N/Z

BEAM

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Experimental Setup

• T1: Si-Si-CsI(Tl)- 2.8° ≤ θLab ≤ 6.6°- Z = 1-55; A for Z = 1-14

124Xe 124Sn 112Sn1.30 1.48 1.24

273µm Si(IP) 1001µm Si(IP) 3.3cm CsI(Tl)/PD

48 rings 16 “pies”

48 rings 16 “pies” 16 “pies”

FIRST: T. Paduszynski et al., NIMA 547, 464 (2005)

124(,136)Xe + 112, 124Sn @ 49.2 MeV/AExperiment performed at GANIL (France)

N/Z

BEAM

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Experimental Setup

• T1: Si-Si-CsI(Tl)- 2.8° ≤ θLab ≤ 6.6°- Z = 1-55; A for Z = 1-14

• T2: Si-CsI(Tl)- 7.3° ≤ θLab ≤ 14.3°- Z = 1-24; A for Z=1-8

124Xe 124Sn 112Sn1.30 1.48 1.24

273µm Si(IP) 1001µm Si(IP) 3.3cm CsI(Tl)/PD

48 rings 16 “pies”

48 rings 16 “pies” 16 “pies”

16 rings (x4 quadrants) 16 “pies”

16 “pies”

3.3 cm CsI(Tl)/PD 500µm Si(IP)

FIRST: T. Paduszynski et al., NIMA 547, 464 (2005)

124(,136)Xe + 112, 124Sn @ 49.2 MeV/AExperiment performed at GANIL (France)

N/Z

BEAM

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Experimental Setup

• T1: Si-Si-CsI(Tl)- 2.8° ≤ θLab ≤ 6.6°- Z = 1-55; A for Z = 1-14

• T2: Si-CsI(Tl)- 7.3° ≤ θLab ≤ 14.3°- Z = 1-24; A for Z=1-8

• LASSA: 36.4° ≤ θLab ≤ 51.5°• DEMON: n TOF

124Xe 124Sn 112Sn1.30 1.48 1.24

273µm Si(IP) 1001µm Si(IP) 3.3cm CsI(Tl)/PD

48 rings 16 “pies”

48 rings 16 “pies” 16 “pies”

16 rings (x4 quadrants) 16 “pies”

16 “pies”

3.3 cm CsI(Tl)/PD 500µm Si(IP)

FIRST: T. Paduszynski et al., NIMA 547, 464 (2005)

124(,136)Xe + 112, 124Sn @ 49.2 MeV/AExperiment performed at GANIL (France)

N/Z

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Aligned Decay Angle between the relative velocity and the fragment “parent” velocity

ZH

ZL

α

TLF*

npvREL

vc.m.

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Aligned Decay

• Asymmetric angular distributions• Larger asymmetry for lighter ZL

• Asymmetry persists up to ZL = 18• Similar yield for n-rich target*

Angle between the relative velocity and the fragment “parent” velocity

ZH

ZL

α

TLF*

npvREL

vc.m.

*: Backward enhancement observed in Sn+Ni for change of target and projectile

P. Russotto et al., PRC 81, 064605 (2010)

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Isotopic Composition vs Rotation Angle

• Backward emission neutron-rich relative to forward emission

• Fragment neutron content enhanced for larger alignment

• No visible target effect of the relative neutron composition

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Relative Velocity Dependence

90°-180°66°-90°37°-66°0°-37°

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Relative Velocity Dependence• ⟨N⟩/Z decreases with vREL for forward decay (Coulomb effect)

• ⟨N⟩/Z increases with vREL for backward decay

90°-180°66°-90°37°-66°0°-37°

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Relative Velocity Dependence• ⟨N⟩/Z decreases with vREL for forward decay (Coulomb effect)

• ⟨N⟩/Z increases with vREL for backward decay

• All backward decays show the same dependence with vREL

90°-180°66°-90°37°-66°0°-37°

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Relative Velocity Dependence

More aligned decay with higher vREL ⇒ observed angular dependence

• ⟨N⟩/Z decreases with vREL for forward decay (Coulomb effect)

• ⟨N⟩/Z increases with vREL for backward decay

• All backward decays show the same dependence with vREL

90°-180°66°-90°37°-66°0°-37°

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Time Extraction

t = 0

• The rotation angle can be related to time via the rotational frequency ω:

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Time Extraction

t =α

ω

t = 0

• The rotation angle can be related to time via the rotational frequency ω:

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Time Extraction

t =α

ω

t

t = 0

• The rotation angle can be related to time via the rotational frequency ω:

•ω in the range 0.7-0.6 1021 rad/s corresponding to based on previous studies*.

� ≈ 40�

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Time Extraction

t =α

ω

*: G. Casini et al., PRL 71, 2567 (1993)

t = T/4

t = 0

• The rotation angle can be related to time via the rotational frequency ω:

•ω in the range 0.7-0.6 1021 rad/s corresponding to based on previous studies*.

• The correlation between <vREL> and the rotation angle is monotonous (5th degree polynom parametrization).

� ≈ 40�

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Time Extraction

t =α

ω

*: G. Casini et al., PRL 71, 2567 (1993)

t = T/4

t = 0

• The rotation angle can be related to time via the rotational frequency ω:

•ω in the range 0.7-0.6 1021 rad/s corresponding to based on previous studies*.

• The correlation between <vREL> and the rotation angle is monotonous (5th degree polynom parametrization).

vREL ⇒ angle ⇒ time

� ≈ 40�

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Time Extraction

t =α

ω

*: G. Casini et al., PRL 71, 2567 (1993)

t = T/4

t = 0

April 1, 2012Sylvie Hudan, APS April Meeting 2012

N/Z Time Dependence

66°-90° 37°-66°0°-37°

1 zs = 10-21 s

April 1, 2012Sylvie Hudan, APS April Meeting 2012

N/Z Time Dependence

• ZL = 4• Strong time dependence• Two components

66°-90° 37°-66°0°-37°

1 zs = 10-21 s

April 1, 2012Sylvie Hudan, APS April Meeting 2012

N/Z Time Dependence

• ZL = 4• Strong time dependence• Two components

• ZL = 5,6• Time dependence not as pronounced as for ZL = 4

66°-90° 37°-66°0°-37°

1 zs = 10-21 s

April 1, 2012Sylvie Hudan, APS April Meeting 2012

N/Z Time Dependence

• ZL = 4• Strong time dependence• Two components

• ZL = 5,6• Time dependence not as pronounced as for ZL = 4

• ZL = 8• Similar dependence for both short and long times

66°-90° 37°-66°0°-37°

1 zs = 10-21 s

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Conclusions

April 1, 2012Sylvie Hudan, APS April Meeting 2012

ConclusionsThe ⟨N⟩/Z of fragments emitted in dynamical decay is correlated with the rotation angle.Different vREL dependence are observed for forward and backward emission.For backward decays, ⟨N⟩/Z increases with vREL with a similar magnitude for all angles.Evolution of ⟨N⟩/Z over 2-3 zs (600-900 fm/c)

April 1, 2012Sylvie Hudan, APS April Meeting 2012

ConclusionsThe ⟨N⟩/Z of fragments emitted in dynamical decay is correlated with the rotation angle.Different vREL dependence are observed for forward and backward emission.For backward decays, ⟨N⟩/Z increases with vREL with a similar magnitude for all angles.Evolution of ⟨N⟩/Z over 2-3 zs (600-900 fm/c)

Difference in ⟨N⟩/Z time dependence for different ZL may be related to differences in the initial di-nuclear configuration (different position relative to saddle and scission points).In the future, use of damped reactions at radioactive beam facilities?

April 1, 2012Sylvie Hudan, APS April Meeting 2012

Collaboration and AcknowledgementsIndiana University: A.B. McIntosh, S. Hudan, J. Black, D. Mercier, C.J. Metelko, R. Yanez, R.T. de Souza

GANIL: A. Chbihi

GSI: S. Bianchin, C. Schwarz, W. Trautmann

Université Laval, Québec: M.O. Frégeau, J. Gauthier, J. Moisan, R. Roy

WMU: M. Famiano

Thanks to:• The support of the GANIL staff and facility• The DEMON collaboration

This work was supported by the DOE Office of Science under the Grant No. DEFG02-88ER-40404