SPES WORKSHOP, Milano, 9 th- 10th Dicember 2013

Prompt collective oscillations with exotic beams

Letter of intent for the SPES-ALPI facility

S. Barlini from INFN-Fi and University of Florence

Subscribers from:

INFN (Fi, Mi, LNL, Bo, Ct, LNS)

LPC, Caen, France

Daresbury, UK;

NIPNE, Romania;

Nevsheir University, Turkey;

IFJ PAN Krakòw, Jagellonian Univ., Warsaw Univ., Poland;

Ohio University, US

The physic case: the Dynamical Dipole Resonance (DDR)

γ

It is a collective dipole oscillation along the symmetry axis occurring at the

beginning of the interaction between charge asymmetric heavy ions

CN

Possible emission

of DDR from a not

equilibrated

source

Possible emission

of GDR in the CN-

decay

SPES WORKSHOP, Milano, 9 th- 10th Dicember 2013

V.Baran et al. PRL 87,2001 and PRC79,2009

M.DiToro et al. EPJ A13 2002

𝐷0 =𝑟0(𝐴𝑝

1/3+ 𝐴𝑡

1/3)

𝐴𝑍𝑝𝑍𝑡

𝑁𝑡𝑍𝑡

−𝑁𝑝

𝑍𝑝

Main features of DDR emission:

• The DDR yield grows as a function of the charge-asymmetry of

the two reaction partners. Usually, the DDR is studied as a

function of the initial dipole moment (D0) of the system,

defined as

• The gamma energy of DDR is shifted to lower values

(around 10 MeV) with respect to GDR emission, as a

consequence of the larger deformation of the system

N/Z

dependence

SPES WORKSHOP, Milano, 9 th- 10th Dicember 2013

• DDR occurs in the range 6-12AMeV:

below 6AMeV the acceleration felt by the charge

distribution is too small

beyond 12AMeV quenched oscillations and high pre-

equilibrium particle emission

Energy range

6-12AMeV

• DDR produces gamma’s with angular distribution peaked

perpendicularly to the interaction axis of the two nuclei

SPES WORKSHOP, Milano, 9 th- 10th Dicember 2013

Some experimental results:

The “standard” technique to disentangle the DDR emission is the comparison

between two reactions (one charge symmetric system with small D0 and one

charge asymmetric system with big D0) producing the same CN.

A.Corsi et al., Phys.Lett.B 679 (2009), 197

B.Martin et al., Phys.Lett.B 664 (2008), 47

D.pierroutsakou, Phys.Rev. C80 (2009), 024612

Reaction Elab

(AMeV)

E*

(MeV)

D0

(fm)

32S+100Mo 6.125 117 18.2

36S+96Mo 5.95 117 1.7

32S+100Mo 9.3 174 18.2

36S+96Mo 8.9 174 1.7

36Ar+96Zr 16 285±9 20.6

40Ar+92Zr 15.1 284±9 4.0

Reaction Elab

(AMeV)

E*

(MeV)

D0

(fm)

64Ni+68Zn 4.7 100 1.2

16O+116Sn 8.1 94±3 8.6

64Ni+68Zn 7.8 200 1.2

16O+116Sn 15 165±7 8.6

It is difficult to extract correctly

the DDR emission, but …

Some examples from LNL and LNS recent experiments

…but in any case:

• pre-equilibrium particles emission should be taken into account

(determination of E*) (importance of LCP detection)

Proton

Alpha

SPES WORKSHOP, Milano, 9 th- 10th Dicember 2013

Moving source technique to separate the evaporation

and pre-equilibrium contribution

• neutrons should be taken into account (from model and

systematics)

• Importance of DDR angular distribution

…but in any case:

SPES WORKSHOP, Milano, 9 th- 10th Dicember 2013

difference

between 36,40Ar+96,92Zr

𝑀𝛾 = 𝑀0 1 + 𝑎2𝑃2(𝑐𝑜𝑠𝜗)

a2=-1

a2=-1 emission from a

dipole oscillating along

the beam axis

40Ar+92Zr 36Ar+96Zr

• Comparison of DDR gamma multiplicity with BNV model

as a function of Ebeam: the dynamic of the interaction

between beam and target influences the DDR strength

…but in any case:

EoS

Different ingredients in model

calculation can be tested:

• Asy-stiff or Asy-soft

• nn cross section

• Etc…

SPES WORKSHOP, Milano, 9 th- 10th Dicember 2013

N/Z dependence

Energy range 6-12 AMeV DDR emission

SPES WORKSHOP, Milano, 9 th- 10th Dicember 2013

The proposed experiment

Reaction N/Z CN D0

(fm)

133Cs+48Ca 1.42 – 1.40 181Re 1.2

142Cs+40Ca 1.58 - 1.00 182Re 36

141Cs+40Ca 1.56 – 1.00 181Re 36

Stable beam

SPES beam

Of course also the

Sn region is

interesting

Reaction N/Z CN D0

(fm)

124Sn+56Fe 1.48 – 1.15 180Os 25

90Kr+90Zr 1.50 - 1.25 180Os 21.5

Possible DDR dependence on the

mass asymmetry between

projectile and target (difference

in the dynamics of interaction)

Reaction N/Z CN

124Sn+58Ni 1.48 – 1.07 182Pt

124Sn+64Ni 1.48 - 1.29 182Pt

132Sn+58Ni 1.64 – 1.07 190Pt

Reaction N/Z CN

124Sn+48Ca 1.48 - 1.40 172Yb

132Sn+40Ca 1.64 – 1.00 172Yb

142Cs : 2* 108pps

141Cs : 2* 107 pps

90Kr : 8.7 107pps

132Sn : 3.1 107 pps

SPES WORKSHOP, Milano, 9 th- 10th Dicember 2013

The experimental apparatus

Evaporation Residue

(and Fission Fragments)

Detection

LCP for pre-

equilibrium estimation Gamma detector

• PPAC

• Phoswich

detectors

• Rco detector

• Mass

spectrometer

• ….

• GARFIELD

• FAZIA

• FARCOS

• TRACE

• ...

• HECTOR

• SERPE

• MEDEA

• PARIS

• …

It is important to detect at the same time the ER, LCP and gamma

rays (with ER-gamma and ER-LCP coincidences). A strong

collaboration among the different experimental groups interested in

this type of experiments should start in order to find what is the best

and most feasible solution that can be implemented.

…and some detectors for neutrons?

Not in

vacuum!

133Cs + 48Ca @10 AMeV: a GEMINI simulation

Z

Theta

Z Z

Counts

Counts

Only ER mechanism

ER FF

ER

FF

Max θER

Reverse

kinematics!

Z

ER

FF

Ela

b

Z

Theta

ER

FF

Z1

Z2

Z1,Z2 are the largest fragments

θZ1

θZ2

Z1,Z2 are well correlated as

emission angle

FF

ER

Asymmetric

Fission

133Cs + 48Ca @10 AMeV: a GEMINI simulation

ToF (ns)

ToF (ns) ToF (ns)

A

A A Theta < 30° Theta < 10°

2m of ToF 2m of ToF

2m of ToF

Simple ToF gate

Z

Elab

ToF (ns)

2m of ToF

133Cs + 48Ca @10 AMeV: a GEMINI simulation

beam

• Narrow angular distribution of ER (θmax<5°)

• Grazing angle of the reaction around 6°

• Contributions from the Fission process to be evaluated (33%

using standard GEMINI parameters)

• Possibility to disentangle Evaporation process from fission

process using ToF (with 2 m of path) at angles θ<10°

We need to work together to find the

best experimental solution!

SPES WORKSHOP, Milano, 9 th- 10th Dicember 2013

133Cs + 48Ca @10 AMeV: a GEMINI simulation

G.Casinia, S. Barlinia, M. Binia, M. Brunob, M. Cinauseroe, M. D'Agostinob, D. Fabrise,

N. Gellia, F. Gramegnae, T. Marchie, L. Morellib, A. Nanninia,A. Olmia, S. Valdrea, G.

Pasqualia, S. Piantellia, G. Poggia, R. Albag, C. Maiolinog, D. Santonocitog, G. Pretee,

A. Braccoc, F. Camerac, A. Corsi c, O. Wielandc, M. Ciemalad, B. Fornald, M. Kmiecikd,

A. Majd, K. Mazurekd, B. Wasilewskad, C.Borceai , M. Parloglp,i, M. Degerlierf , T.

Kozikju, A. Kordyaszwa, P. Kuligju, Z. Sosinju, A. Wielochju, T. Twarogju, D. Sierpowskiju,

M. Kajetanowiczju, J. Lukasikd,K. Korcyld,B. Klossi, S. Kowalskisi, A. Grzeszczuksi,W.

Zippersi, M. Chartierh, R. Lemmonh, Z. Basrakz, M. Milinz, N. Soicz, S. Szilnerz, A.

Voinovoh, M.Colonnag, M.Di Torog, C.Rizzog, V.Barani

a INFN, Sezione di Firenze and Dipartimento di Fisica dell'Università, Firenze, Italy b INFN, Sezione di Bologna and Dipartimento di Fisica dell'Università, Bologna, Italy c INFN, Sezione di Milano and Dipartimento di Fisica dell'Università, Milano, Italy d H. Niewodniczanski Institute of Nuclear Physics PAN, Krakow, Poland e INFN, Laboratori Nazionali di Legnaro, Italy f Nevsehir University of Science and Art Faculty Physics Department, Nevsheir, Turkey g INFN, Laboratori Nazionali del Sud , Catania, Italy h Daresbury Laboratory, Cheshire, United Kingdom i NIPNE-HH and Bucharest University, Romania wa University of Warsaw, Poland ju Jagellonian University, Krakow, Poland si Silesian University, Katowice, Poland oh Ohio University , US lp LPC, Caen, France z R. Boskovic Institute, Zagreb, Croatia

A.Corsi et al., Phys.Lett.B 679 (2009), 197

D.pierroutsakou, Phys.Rev. C80 (2009), 024612

Different methods to extract the DDR emission

40Ar+92Zr 36Ar+96Zr

difference

DDR yield obtained as a

comparison with statistical code.

DDR yield obtained as a difference

between the two charge-

symmetric reactions.

SPES WORKSHOP, Milano, 9 th- 10th Dicember 2013