status of the magnetic spectrometer prisma -...

Meeting on gas and Si detectors for the PRISMA and VAMOS spectrometers GANIL, October 2nd, 2008

E. Fioretto - LNL1

Status of the magnetic spectrometer PRISMAStatus of the magnetic spectrometer PRISMA

E. FiorettoINFN – Laboratori Nazionali di Legnaro

E. FiorettoINFN – Laboratori Nazionali di Legnaro


E. Fioretto - LNL2

PRISMA in PRISMA in vacuumvacuum modemode

Target

Beam

Rotating platform

Quadrupole

30 cm

50 cm

Dipole 60°120 cm

-20°

+130°

PRISMA: a large acceptance magnetic spectrometer

Ω≈ 80 msr; Bρ = 1.2 TmΔA/A ~ 1/200Energy acceptance ±20%


E. Fioretto - LNL3

PRISMA : the Start detectorPRISMA : the Start detector

Quadrupole Dipole

Target

X

Y

MCP

Δt ~ 350 ps, ΔX, ΔY ~ 0.5 mm

G. Montagnoli et al. NIM A547, 455 (05)


E. Fioretto - LNL4

PRISMA : the PRISMA : the FocalFocal PlanePlane DetectorDetector

Quadrupole Dipole

Target

S. Beghini et al. NIM A551, 364 (05)

X position

Δt ~ 300 ps, ΔX, ΔY = 1 mm

MWPPAC


E. Fioretto - LNL5

PRISMA : the PRISMA : the FocalFocal PlanePlane DetectorDetector

Quadrupole Dipole

Target

Z=30

ΔE/E < 2%Z/ΔZ ~ 60 for Z=20

Ionization chamber70Zn+238U


E. Fioretto - LNL6

CLOVER CLOVER arrayarray (up (up toto MarchMarch 2008)2008)

Quadrupole Dipole

23 EUROBALL CloversEfficiency ~ 3 % (Eγ= 1.3 MeV) FWHM = 0.9% (for β=10%)Peak/Total ~ 45% CLARA


Shell evolution @ N=20/32/34/50/82Collectivity (deformation) and dynami-cal symmetriesLifetime measurementsPairing vibrational statesMolecular resonancesMultinucleon transfer reactions

E. Fioretto - LNL7

MainMain topicstopics of the PRISMAof the PRISMA--CLARA CLARA campaigncampaign

Grazing reactions as a tool to study nGrazing reactions as a tool to study n--rich nucleirich nuclei


36Si

E. Fioretto - LNL8

AroundAround the the islandisland of of inversioninversion

00+

14082+

(4+)

(6+)

2850

3692PRISMAθ=56°

36S+208Pb @ 215 MeV X. Liang et al., PRC 74, 014311 (2006)

rotor

vibrator

Eγ (keV)

CLARA


E. Fioretto - LNL9

ExploringExploring the the 4848Ca Ca regionregion

48Ca@ 310MeV

natMg

β≈10.0%β’≈8.0%

dDegrader Target

Eγ’ Eγ

@ θg for BLF

208Pb

Differential Plunger

PRISMA

CLARA

RDDS method

48Ca+238U @ 310 MeV

Mass resolution after degrader is preserved

Eγ Eγ’

Eγ’: Doppler corrected


J.J. Valiente-Dobón et al., LNL AnnualReport 2007 and to be published

E. Fioretto - LNL10

ExploringExploring the the 4848Ca Ca regionregion

IuIs

Ca (2+)

( ) 42fme5057022ps796

..:EB ±=→

±=τ++

( ) 42fme424272112ps425

±=→

±=τ−− //:EB

50Ca

51Sc

The measured transition probability in 50Ca is lower than in doubly-magic 48Ca, in agreement with shell-model calculations (tuned with previous experiments in the mass region)

Transition probabilities


E. Fioretto - LNL11

SpectroscopySpectroscopy of of heavyheavy Cr Cr isotopesisotopes64Ni+238U @ 404 MeV N. Mărginean et al., PLB 633 (2006) 696

γ rays from the yrast levels of 58Cr observed for the first time


58Cr

E. Fioretto - LNL12

γγ--softnesssoftness in in heavyheavy Cr and Fe Cr and Fe isotopesisotopes64Ni+238U @ 404 MeV

N. M

ărgineanet al.,

PLB

633(2006) 696

The R(E4/E2) ratio for the heavy Fe isotopesis very close to the 2.50 value characteristicof γ-soft rotors (S. Lunardi et al., PRC 76, 034303 (2007))58Cr lies exactly at the 2.20 value predictedfor the E(5) dynamical symmetry. The energies of the yrast band are in goodagreement with the predictions.

F.Ia

chel

loP

RL8

5, 3

580

(200

0)


Scientific output24 experiments (Jan 2004 - Mar 2008) 16 papers + 2 submittedOver 40 presentations at international conferences/workshops

User Access~ 50% of the total beam-time of the Tandem/PIAVE-ALPI accelerator complex of INFN-LNL~ 200 European users most of them supported within the Transnational Access activity of the EC-contract EURONS

Education8 thesis (diploma, PhD, …)

Support (research contracts)8 person-years funded by INFN5 person-years for Nuclear Structure Based Facilities funded by EC through EURONS (only partly devoted to PRISMA-CLARA)

E. Fioretto - LNL13

SummarySummary of the PRISMAof the PRISMA--CLARA CLARA campaigncampaign


E. Fioretto - LNL14

The AGATA The AGATA demonstratordemonstrator at LNLat LNL

1 symmetric triple-cluster5 asymmetric triple-clusters

36-fold segmented crystals555 digital-channelsEff. 3 – 7 % @ Mγ = 1Eff. 2 – 4 % @ Mγ = 30

Full DAQwith on-line PSA and γ-ray tracking

In beam CommissioningFirst test site: LNL

Telescopic beam line

Support frame

LN2 line

The first subset of AGATA (the Demonstrator Array) will soon start operation at the Laboratori Nazionalidi Legnaro. The installation is in progress.

23 LOIs – 16 Institutions

CLARA vs.AD

PR

ISM

A +

AD

+ P

lung

erP

RIS

MA

+ C

LAR

A +

Plu

nger


E. Fioretto - LNL15

PRISMA in PRISMA in GasGas--FilledFilled modemode

Detector chamberfor GFM

Magneticdipole

Gas-flow control system

The new detector-chamber mounted on PRISMA


E. Fioretto - LNL16

PRISMA in PRISMA in GasGas--FilledFilled modemode

0,5

0,7

0,9

1,1

1,3

1,5

1,7

1,9

0,01 0,10 1,00 10,00E/A (MeV/amu)

Bρ

(Tm

)

58Ni

112Sn

148Sm

176Hf

208Pb

252Fm

<q> according to Betz

Problems with magnetic rigidity

PRISMA max rigidityfor central trajectories

cross sections are known, so it isan ideal case for validating the simulations

the average charge state can bevery low in gas for a slow, heavyion

for a central trajecto-ry Prisma is limited to A<180

by using non-central trajectorywe can reach Bρ = 1.5 Tm

TmB 2.1≤ρ


RecoilRecoil detectorsdetectors

E. Fioretto - LNL17

2 x 3 SSD, 300 μm thick, 5x5 cm2

16 resistive strips

Si-strip detectorsfor PRISMA in GFM


16 P

A –

box

(1 S

i det

ecto

r)To

tal o

f abo

ut10

0 si

gnal

s

Junc

tion

side

3mmoh

mic

side

RecoilRecoil detectorsdetectors and and electronicselectronics

E. Fioretto - LNL18

Home-made PA


Scattering Scattering chamberchamber

E. Fioretto - LNL19

beam

beam stoppermonitor

CF window “nose” GSI windows

(gas side)

LNL windowsbeam side

Conditions of the beam test


InIn--beam testsbeam tests

E. Fioretto - LNL20

Elastic scattering reaction below Coulomb barrier

58Ni+197Au @ 160 MeV, PRISMA @ 55°

the heavy recoils simulate typical ERs without the complications of a 0°measurementcross sections are known, so it is an ideal case for validating the simulationsit is also possible to measure the position spectrum of the “beam”

Measurementsvarying the dipole field, for each pressure centering the “ER” ontothe FPDvarying the quadrupole field for best transmission and resolutiondifferent gas pressures (1 mbar and 3 mbar)tests with different gas would also be of interest


InIn--beam tests (Junebeam tests (June--July 2007)July 2007)

E. Fioretto - LNL21

fwhm ~ 15cm

0

10

20

30

40

50

60

70

80

0,07 0,12 0,17 0,22

BD (a.u.)

cont

.

α-calibration

X-E

nerg

y m

atrix

and

pos

ition

spe

ctru

m


E. Fioretto - LNL22

SummarySummary of of performedperformed teststests

PRISMA in GFMAdequate Bρ up to masses A~200Focal plane detector : 6 Si strips detectors ≈ 10 × 15 cm2

Aim : fusion reactions studies (no SHE)

Tests performedElectronics tests with Si and α-sourceC-foil window leak tested with different gasesIn-beam tests 58Ni (160 MeV)+197Au, PRISMA @ 55° (July ‘07)

Test of spot sizebeam separation vs energy and gas

Future stepIn beam test @ 0°

to measure a fusion reaction in full operating condition

PRISMA in GFMAdequate Bρ up to masses A~200Focal plane detector : 6 Si strips detectors ≈ 10 × 15 cm2

Aim : fusion reactions studies (no SHE)

Tests performedElectronics tests with Si and α-sourceC-foil window leak tested with different gasesIn-beam tests 58Ni (160 MeV)+197Au, PRISMA @ 55° (July ‘07)

Test of spot sizebeam separation vs energy and gas

Future stepIn beam test @ 0°

to measure a fusion reaction in full operating condition


E. Fioretto - LNL23

SummarySummary

PRISMA+CLARA24 experiments (Jan 2004 - Mar 2008)~ 200 European users~ 50% of the total beam time of the Tandem/PIAVE-ALPI accelera-tor complex

PRISMA+AGATA DemonstratorThe installation of the AGATA Demonstrator around the target area of PRISMA is in progress (EURONS – JRA02-AGATA)The first experimental campaign for reaction mechanism and nuclear structure studies with PRISMA+AD in 2009

PRISMA in GFM (EURONS – JRA06-INTAG)Recoil detector and home-made electronics successfully tested with PRISMA not @ 0°

PRISMA+CLARA24 experiments (Jan 2004 - Mar 2008)~ 200 European users~ 50% of the total beam time of the Tandem/PIAVE-ALPI accelera-tor complex

PRISMA+AGATA DemonstratorThe installation of the AGATA Demonstrator around the target area of PRISMA is in progress (EURONS – JRA02-AGATA)The first experimental campaign for reaction mechanism and nuclear structure studies with PRISMA+AD in 2009

PRISMA in GFM (EURONS – JRA06-INTAG)Recoil detector and home-made electronics successfully tested with PRISMA not @ 0°

status of the magnetic spectrometer prisma -...

Documents