prisma - Istituto Nazionale di Fisica Nuclearedetectors/prisma.pdf · PRISMA Spectrometer E....

PRISMA PRISMA SpectrometerSpectrometer

E. FiorettoINFN - LNL

Target

Beam

Rotating platform

Focal plane

Quadrupole

Start detector

30 cm

50 cm

Dipole60°

120 cm

-20°

+130°

INTAG meetingJanuary 27th, 2005 - Jyväskylä

Prisma CLARA Set-up

25 CLOVER detectors from EUROBALL

Angular acceptances Δθ ~ ±6o Δφ ~ ±11o

Solid angle ΔΩ ~ 80 msr

Distance target-FPD 7 m

Energy acceptance ± 20%

Momentum acceptance ± 10%

Maximum rigidity ME/q2 = 70 MeV amu

Dispersion 4 cm/%

Energy resolution 1/1000 (via TOF)

Mass resolution 1/300 FWHM (via TOF)

Aberrations correction via software

Angular acceptances Δθ ~ ±6o Δφ ~ ±11o

Solid angle ΔΩ ~ 80 msr

Distance target-FPD 7 m

Energy acceptance ± 20%

Momentum acceptance ± 10%

Maximum rigidity ME/q2 = 70 MeV amu

Dispersion 4 cm/%

Energy resolution 1/1000 (via TOF)

Mass resolution 1/300 FWHM (via TOF)

Aberrations correction via software


Design Characteristics of PRISMADesign Characteristics of PRISMA


The Start DetectorThe Start Detector

Developed in the collaboration: INFNDeveloped in the collaboration: INFN--PadovaPadova, , JINR JINR DubnaDubna, INFN, INFN--LNL LNL

The readout of the anode is based on two The readout of the anode is based on two orthogonal delay lines.orthogonal delay lines.The delay lines are homeThe delay lines are home--made using 70 made using 70 µµm m diameter Cudiameter Cu--Be wires.Be wires.Timing Timing resolutionresolution ~ ~ 350 350 psps


∅∅=1mm =1mm

ηη=1.1mm (FWHM)=1.1mm (FWHM)

•• ItIt isis basedbased on on MicroMicro--ChannelChannel PlatePlate•• activeactive area area 80x100 mm80x100 mm22

•• ddtargettarget = = 25 cm from the target25 cm from the target•• a thin a thin Carbon foilCarbon foil ((20 20 μμg/cmg/cm22) is ) is passedpassed byby

the the particlesparticles at an angle of 135at an angle of 135°°•• EaccEacc ~~ 3030--40 40 kVkV/m/m d(C d(C foilfoil//gridgrid) =) = 1cm1cm•• B B ~~ 120 Gauss120 Gauss

XX

YY


The Focal Plane Detector: MWPPACThe Focal Plane Detector: MWPPAC

Active area of the FPD:Active area of the FPD:100x13 cm100x13 cm22

MWPPACMWPPAC

CathodeCathode

Anode Anode YY

Al frameAl frame

Al frameAl frameAnode Anode XX


S.Beghini et al.- LNL Ann. Rep. 2000 p.163

Filling gas : CFilling gas : C44HH10 10 Working pressure : 7 Working pressure : 7 hPahPa


The Focal Plane Detector: ICThe Focal Plane Detector: IC

10 x 4 sections10 x 4 sections10x25 cm10x25 cm22

ICIC


E.Fioretto et al.- LNL Ann. Rep. 2002 p.148

0 10 20 30 40 50 604

6

8

10

12

14

16

18 132Xe

80Se56Fe40Ca35Cl

16O

Ion

Ene

rgy

(MeV

/u)

Atomic Number

CH4

CF4 C4H10

CH4 Si100 hPa 59 μmCHCH4 4 SiSi100 100 hPahPa 59 59 μμmm

CF4 Si100 hPa 168 μmCFCF4 4 SiSi100 100 hPahPa 168 168 μμmm

Maximum working pressure: Maximum working pressure: 100 100 hPahPa

100 cm


InIn--beam testsbeam tests

ΔΔE/E < 2%E/E < 2%Z/Z/ΔΔZ ~ 60 for Z=20Z ~ 60 for Z=20

ΔΔtt ~ 300 ~ 300 psps, , ΔΔX, X, ΔΔY = 1 mmY = 1 mm

195 MeV 195 MeV 3636S + S + 208208Pb, Pb, θθlablab = 80= 80oo

E (E (a.ua.u.).)

ΔΔE

(E

( a.ua.u .

).)

Z=16Z=16

Z=28Z=28240 MeV 56Fe+124Sn, θlab = 70°

E (E (a.ua.u.).)

ΔΔE

(E

( a.ua.u .

).)

Z=26

X position X position


Y positionY position


InIn--beam tests : energy resolutionbeam tests : energy resolution

235 235 MeVMeV 4040Ca+Ca+208208PbPb PRISMAPRISMA @ @ θθlablab = 90= 90oo


X (X (a.ua.u.).)

Coun

tsCo

unt s

Inelastic excitations Inelastic excitations of of

octupoleoctupole vibrationsvibrations

The deduced energy resolution is roughly 700 The deduced energy resolution is roughly 700 keVkeV, or 1/300., or 1/300.

Position (energy) spectrumPosition (energy) spectrum

gated on A=40 and Z=20 with the condition of a narrow cone in the entrance MCP detector

2.614 2.614 MeVMeV


InIn--beam tests : mass resolutionbeam tests : mass resolution

260 260 MeVMeV 5858Ni+Ni+124124Sn, Sn, θθlablab = 70= 70oo

PPAC section #7PPAC section #7

XX

TOF

TOF

A/qA/q

58/1958/19++

59596060

A mass resolution of about 1/220 has been measured A mass resolution of about 1/220 has been measured for neutron pickfor neutron pick--up channelsup channels


gated by a 10 mm × 40 mm window in the (X,Y) matrix of the entrance MCP detector

Z=28 events selected in the IC.Z=28 events selected in the IC.


First experimental campaign


Shell model in 37P and 39PBreaking of a semi-magic shell

closure far from stability


82Se+238U

36S+208Pb15

2032S+58Ni

Mirror pair 31S and 31P

54Fe+50CrSpectroscopy of 54Co Isospin non conservingpart of the effective

interaction

64Ni+238UShell model A~60

Shell closure evolution at Shell closure evolution at the magic number N=50the magic number N=50

50

32

Multi-nucleon transfer

Resonances in 24Mg+24Mg and molecular states in 48Cr

27

2840Ca+208Pb

Pairing-vibration states in 42Ca

90Zr+208Pb

24Mg+24Mg

Large-angle scattering

58Ni+60Ni

EE

proton stripping

channels

proton pick-up channels

fission eventsZ=50

Z=34

AprilApril 20042004

ΔΔEE

505 MeV 82Se+238U PRISMA at 64°

Element identification



Detector thicknessDetector thickness


C foil20 μg/cm2 thick

Mylar foils1.5 μm thick

~ 600 μg/cm2

PRISMA meetingMarch 14th, 2005 - LNL

Mass distributions of reaction productsMass region : A=60-90

Se

As

Br

Kr

Ge

Ga

Zn

Cu

Ni

82

838481

80

77

76

89

8182

7978

808179

78

69

7778

7473

7475

73

7170

6768 72

6564 7170

69

8685

87

81

84 8883

A

505 MeV 82Se+238U PRISMA at 64°

E. Fioretto / INFN - LNL

beam

εεPPACPPAC~100%~100%

7776

75

78 7776

75

74

7980

81

8283

78 7776

75

74

7980

81

8283

GeGe


INTAG meeting - January 27th, 2005 - Jyväskylä

279

227

121

139

466524352

104011331086

the isomeric 237keV transition is missing in the CLARA-

PRISMA spectrum!

Transitions identified for first time with CLARA-PRISMA

2+→ 0+

8+→ 6+6+→ 4+

4+→ 2+

10+→ 8+

Gammasphere, 64Ni+208PbEur.Phys.J. A 9 (2000) 183

CLARA-PRISMA singles Spectrum

(-6p

-4n)

72Zn

80As(-1p -1n)

Level scheme from a thicktarget GASP exp.

460 MeV 82Se on 192Os

CLARA data



Mass distributions of reaction products

Zr isotope populationZr isotope population

Events of each line have the same A/q

q=30q=31 q=29

Mass region : A=80-90

560 MeV 90Zr+208Pb PRISMA @ 62°

Z=40 events selected in the ICZ=40 events selected in the IC




A mass resolution of about 1/280 has been measured A mass resolution of about 1/280 has been measured

Mass distributions of reaction products


122 MeV 32S+58Ni

92 MeV 24Mg+24Mg

12C

13C

16O

20Ne

21Ne19Ne

24Mg

25Mg

28Si

Mass region : A=12-32




Future Future taggingtagging developmentsdevelopments


Low efficiency for light-ions (60-70%)Low efficiency for lightLow efficiency for light--ions (60ions (60--70%)70%)


Heavy ions (Heavy ions (E<10 E<10 MeVAMeVA; Z>10; Z>10))

Emissive foil (Emissive foil (VVff = 10 kV= 10 kV))Mylar 0.6 Mylar 0.6 μμm + Al 30 nmm + Al 30 nm

EE

BB

0 V0 V

Accelerating grid (Accelerating grid (VVgg = 0 V= 0 V))

ExtractionExtractionAccelerationAcceleration

GuidingGuidingFocusingFocusing

Detection Detection LPMWPCLPMWPC

Thin window (Thin window (0.9 0.9 μμmm))

PPACPPAC

MWPCMWPCY strips (Wires)Y strips (Wires)

X stripsX strips0 V0 V

HV +HV +

CC44HH1010 –– 5hPa5hPa ΔΔtt ~ 150 ~ 150 pspsΔΔX, X, ΔΔY ~ 2 mmY ~ 2 mm

MylarMylar cathodecathode SeSe--DDSecondarySecondary electronselectrons

TransparencyTransparency ~ ~ 94%94% HigherHigher transparencytransparency

New New MWPPACsMWPPACs


Low efficiency for light-ions (60-70%)Low efficiency for lightLow efficiency for light--ions (60ions (60--70%)70%)

MylarMylar cathodecathode

wires wires ØØ==10 10 μμm m

Future Future taggingtagging developmentsdevelopments

EE

BB

Heavy ions (Heavy ions (E<10 E<10 MeVAMeVA; Z>10; Z>10))

Emissive foil (Emissive foil (VVff = 10 kV= 10 kV))Mylar 0.6 Mylar 0.6 μμm + Al 30 nmm + Al 30 nm

0 V0 V

Accelerating grid (Accelerating grid (VVgg = 0 V= 0 V))ExtractionExtractionAccelerationAcceleration

GuidingGuidingFocusingFocusing

Detection Detection LPMWPCLPMWPC

Thin window (Thin window (0.9 0.9 μμmm))

PPACPPAC

MWPCMWPCY strips (Wires)Y strips (Wires)

X stripsX strips

0 V0 V

HV +HV +

CC44HH1010 –– 5hPa5hPa ΔΔtt ~ 150 ~ 150 pspsΔΔX, X, ΔΔY ~ 2 mmY ~ 2 mm


New FPD for low energy HI New FPD for low energy HI SeSe--DD

Collaboration with UK groups Manchester (Se-D) - Daresbury (ASIC)

Collaboration with UK groups Collaboration with UK groups Manchester (SeManchester (Se--D) D) -- DaresburyDaresbury (ASIC)(ASIC)

~ ~ 400 400 μμg/cmg/cm22

~ ~ 80 80 μμg/cmg/cm22


SeSe--DD prototypeprototype

Emissive foilEmissive foil

Magnetic field boxMagnetic field box

SeSe--D with mask in VAMOSD with mask in VAMOS

E. FiorettoINFN - LNLPRISMA meeting - February 15th, 2005

ElectronicsElectronics

2x16 analogic channelsSensibility: 3.6 V/pCPeaking time: 1.2 msSerial outputRead-out: Caen RAMS

Gas32 Gas32 boardboard

ASIC ASIC electronicselectronicsApplication Specific Integrated CircuitApplication Specific Integrated Circuit E. Fioretto

INFN - LNLPRISMA meeting

February 15th, 2005

IsomersIsomers



What is an isomer?Metastable (long-lived) excited nuclear state.

Why/When do you get isomers?If there is•large change in spin (“spin-trap”)•dramatic change in structure (shape, K-value)

What do isomers tell you?Isomers occur due to single-particle structure.K-isomers probe both single particle and collective structure.

What is an isomer?Metastable (long-lived) excited nuclear state.

Why/When do you get isomers?If there is•large change in spin (“spin-trap”)•dramatic change in structure (shape, K-value)

What do isomers tell you?Isomers occur due to single-particle structure.K-isomers probe both single particle and collective structure.

ShortShort--lived isomers lived isomers

Promptγ’s

g.s. τ

Isomerτ


τ ≤ 10 ns


LongLong--lived isomerslived isomers


Delayedγ’s

g.s. τ

τ

β

4 CLOVERs detectors

A wall of 40 Si detectors300 μm thick

Active area = 5 x 5 cm2

16 resistive strips


400 ns ≤ τ ≤ 1 μs

OperationOperation in in GasGas--FilledFilled ModeMode

• ER recoiling at or near to 0°• Loss of mass and energy resolution

→ separation of the ERs from the beam particles• PRISMA as separator rather than a spectrometer• Filling gas and working pressures

→ simulations are in progress• Ion species efficiently focused onto a small area at the

the exit of the magnetic dipole (10 x 15 cm2)• The large area of the FPD is not required

→ modification of the FPD• Small dead thickness (no Mylar window)

•• ER recoiling at or near to 0ER recoiling at or near to 0°°•• Loss of mass and energy resolutionLoss of mass and energy resolution

→ separation of the ERs from the beam particlesseparation of the ERs from the beam particles•• PRISMA as separator rather than a spectrometerPRISMA as separator rather than a spectrometer•• Filling gas and working pressuresFilling gas and working pressures

→ simulations are in progresssimulations are in progress•• Ion species efficiently focused onto a small area at the Ion species efficiently focused onto a small area at the

thethe exit of the magnetic dipole (exit of the magnetic dipole (10 x 15 cm10 x 15 cm22))•• The large area of the FPD is not required The large area of the FPD is not required

→ modification of the FPDmodification of the FPD•• Small dead thickness (Small dead thickness (no Mylar windowno Mylar window))

-- Fusion reactions in heavy systemsFusion reactions in heavy systems-- ImplantationImplantation--decay studies (RDT technique)decay studies (RDT technique)-- OffOff--beam spectroscopy beam spectroscopy


INTAG Workshop June 8-9, 2005 - Saclay

Limitations due to the magnetic rigidity

• The average charge state in gas ismuch smaller than in a solid(vacuum), especially at low energy

• Using a central trajectory (Bρ <1.2 Tm) we are limited to A < 180

• With a shift of 30 cm from the central trajectory we can exceedBρ = 1.5 Tm.

• Because of the increase in Bρ at low energy, the rigidity of ERs istypically larger than the beam’s.

• The ratio (BρBEAM)/ (BρER) dependson the energy: careful planning of experiments.

SimulationSimulation resultsresults



EntranceEntrance windowwindow

OperationOperation in in GasGas--FilledFilled ModeMode

DipoleDipole

QuadrupoleQuadrupole

beambeam

FillingFilling gas gas HeHe at P = 1hPaat P = 1hPaANAMARI and TRAJIG ANAMARI and TRAJIG codescodes

1 m

Gas: Gas: 44HeHe

172Y(48Ca, 4n)216ThE = 200 MeV



TaggingTagging detectorsdetectors forfor the GFM the GFM phasephaseJu

nction

Junc

tion

side

side

Ohm

icOhm

icside

side

3 mm3 mm

A A matrixmatrix of 2 x 3 Si of 2 x 3 Si detectorsdetectorsThicknessThickness == 300 300 μμmmActiveActive area = 5 x 5 cmarea = 5 x 5 cm22, 16 , 16 resistiveresistive stripsstrips

SiSi strip detectors for implantation of recoil nucleistrip detectors for implantation of recoil nuclei

PA PA 4 mV/4 mV/MeVMeVAmplAmpl 16 16 chch~ ~ 100 100 electronic

electronicchannels

channels



PRISMA PRISMA collaborationcollaboration

E.Fioretto, A.M. Stefanini, L. Corradi, B.R.Behera, G.de Angelis, A.Gadea, A.Latina, G.Maron, D.R.Napoli, A.Pisent, S.Szilner,

M.Trotta, Y.W. Wu(INFN - LNL)

S.Beghini, G.Montagnoli, F.Scarlassara(Università di Padova and INFN - Padova)

A. De Rosa, G.Inglima, M. La Commara, D.Pierroutsakou, M.Romoli, M.Sandoli

(Università di Napoli and INFN - Napoli)

G.Pollarolo (Università di Torino and INFN - Torino)

D.Ackermann (Univ. of Mainz and GSI, Darmstadt, Germany)

E.FiorettoE.Fioretto, A.M. , A.M. StefaniniStefanini, L. , L. CorradiCorradi, , B.R.BeheraB.R.Behera, G.de Angelis, , G.de Angelis, A.GadeaA.Gadea, A.Latina, , A.Latina, G.MaronG.Maron, , D.R.NapoliD.R.Napoli, , A.PisentA.Pisent, , S.SzilnerS.Szilner, ,

M.TrottaM.Trotta, Y.W. Wu, Y.W. Wu(INFN (INFN -- LNL)LNL)

S.BeghiniS.Beghini, , G.MontagnoliG.Montagnoli, , F.ScarlassaraF.Scarlassara((UniversitUniversitàà didi PadovaPadova and INFN and INFN -- PadovaPadova))

A. De Rosa, A. De Rosa, G.InglimaG.Inglima, M. La , M. La CommaraCommara, , D.PierroutsakouD.Pierroutsakou, , M.RomoliM.Romoli, , M.SandoliM.Sandoli

((UniversitUniversitàà didi NapoliNapoli and INFN and INFN -- NapoliNapoli))

G.PollaroloG.Pollarolo ((UniversitUniversitàà didi TorinoTorino and INFN and INFN -- TorinoTorino))

D.Ackermann D.Ackermann (Univ. of Mainz and GSI, Darmstadt, Germany)(Univ. of Mainz and GSI, Darmstadt, Germany)



High High spinspin studiesstudies in the in the 7878NiNi and and 132132Sn Sn regionregion

p/Q

ISOL ISOL facilityfacility

Multi-nucleon transfer reactions from grazing to D.I. collisionsMultiMulti--nucleon transfer reactions from grazing to D.I. collisionsnucleon transfer reactions from grazing to D.I. collisions

Coulex, elastic and inelastic excitationsCoulexCoulex, elastic and inelastic excitations, elastic and inelastic excitations

Structure of moderately neutron-rich nuclei populated with binary reactions, in combination with CLARAStructure of moderately neutronStructure of moderately neutron--rich nuclei populated with rich nuclei populated with binary reactions, in combination with CLARAbinary reactions, in combination with CLARA

Near- and sub-barrier fusion of heavy systems, dynamical and shell effectsNearNear-- and suband sub--barrier fusion of heavy systems, dynamical and barrier fusion of heavy systems, dynamical and shell effectsshell effects

Future experiments with radioactive ion beamsFuture Future experimentsexperiments withwith radioactiveradioactive ionion beamsbeams

MainMain physicsphysics guideguide--lineslinesXTU Tandem/PIAVE+ALPI beams PRISMA+CLARAXTU Tandem/PIAVE+ALPI beams PRISMA+CLARA


A

Z

Properties of the nuclear residual Properties of the nuclear residual interactioninteractionEvolutionEvolution of the of the singlesingle--particleparticle levelslevels

40Ca

p p st

ripp

ing

stri

ppin

g

n pickn pick--upup

235 MeV 40Ca + 208Pb

Interaction potential (deformation)Interaction potential (deformation)CollectivityCollectivity


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