Application of RFD and other ancillary detectors for

advanced γ-ray spectroscopy with GASP array

Witek Meczynski IFJ PAN Krakow

Rec

oil F

ilter

Det

ecto

r & E

UR

OB

ALL

IV

RFD at EB IV

exp. methods

RFD at GASP

application

Workshop on „Future of Gamma Spectroscopy at LNL: GASP and CLARA arrays”Legnaro-Padova, March 3-5, 2004

Principle of operation

t

Time of Flight

evap.residues

T

beam

fissi

onC

oule

x

beam

0

Recoil Filter Detector at EB IV

RFD:18 individual detectorsToF = 50 – 700 ns = 0.5 – 7%

EB IV:15 Clusters 4.5%26 Clovers 4.0%209 Ge-crystals 8.5%

Advantage and difficulty

141 MeV 28Si + 1.0 mg/cm2 175Lu67 MeV 18O + 0.8 mg/cm2 30Si 2 pnA, 300 ns ~ 3 MHz !

recoil 45Sc

RFD eff. 40%

dN/d

θ

RFD0.24%

scatt. beam

dN/d

θ

scattering angle θ scattering angle θ

Individual RFD element

Mylar 500 nm Al 20 nm

signal ~ ne ~ dE/dxrecoil> 5 MeV foil

- U (kV)

equipotential lineselectron trajectoriest < 5 ns

cylindricalelectrodes

plastic scintillatorphotomultipliere_~20 eV

- 20 kV

recoil

50 mm

EUROBALL IV & Recoil Filter Detector

Filtering of heavy recoils

200 300 400 5000

400

800

1200

coun

ts

γγ−recoil

100

γ-ray energy (keV)

220Th221Th219Ra218Ra217Ra

Th X-rays

γ−γ Pb X-rays

92 MeV 16O + 208Pb 224Th< β > = 0.8%

Predictions for lighter recoils

68 MeV 20Ne + 1 mg/cm2 40Ca 57Ni + 2pn

evaporation of 2pn

57Ni

evaporation and straggling

= 2.1%∆β/β = 33%∆ΘR = 6.7

o

∆ΘGe = 5.0o

∆Eγ ~ 25 keVEγο = 1 500 keV

K.M.Spohr, PhD thesis, HMI, Berlin, 1995

Experimental energy resolution

67 MeV 18O + 0.8 mg/cm2 30Si = 2.8%

single Ge-crystal of CLUSTER

resolving power Ro = 2 - 5

p2nα2n2αn

P.Bednarczyk et al., Acta Phys. Polon. B32,747(2001)

Selection of exit channel:RFD

125 MeV 28Si + 0.4 mg/cm2 28Si

S.Lenzi et al., to be published

Lifetime estimation

R = AA+B

67 MeV 18O + 0.8 mg/cm2 30Si< β > = 2.8%

P.Bednarczyk et al., to be published

Example: terminating state in 44Sc

Sc4421

rel.

exc.

ene

rgy

(MeV

)

44Sc46V43Ca45Sc

π(d3/2)-1(f7/2)2ν(f 7/2)3

I(I+1)

M. Lach et al., Eur. Phys. J A (2004), to be published

Selection of exit channel:RFD - EUCLIDES

125 MeV 16O + 0.4 mg/cm2 56Fe = 2.9%

EUCLIDES:4π charge particle detector

40 Si ∆E-E telescopes

J.Dobaczewski, K.Zuber, P.Bednarczyk et al., Crete Conf., 2003

Example: SD band in 61Cu

τ < 10 fs β > 0.5

J.Dobaczewski, K.Zuber, P.Bednarczyk et al., Crete Conf., 2003

Partial summary

Features:good selection of evaporation residues

Requirements and (present) limits:pulsed beam

high efficiency: 20 – 50%

precise Doppler broadening correction

cross section: > 50 µbcounting rate: < 3 MHz

coupling with another anc. detectors

energy of recoils: > 4 MeVdetection angle: > 2o

short lifetime estimation

resolving power: 2 - 5

RFD at GASP

GASP sphereBGO ball

9obeam

RFD at GASP

RMS

GASP RFD

100 cm

Pb wall

column

BGO ball support

other ancillaries(Si-ball, e--sp.,plunger,...)

beam

Development and perspectives

GASP & RFD &

BGOISIS

e--spectrometerplungerHECTOR.............

!

(EUCLIDES)

Present: VME standard: 2D-analysisPMT stability

CVD diamond foilsFuture:

granularity

Perspectives:

The Recoil Filter Detector team:

IFJ PAN, KrakowP. BednarczykJ. GreboszM. LachA. MajJ. StyczenM. ZieblinskiK.ZuberW. M.

HMI, BerlinK.H. Maier

IReS, StrasbourgJ.C. Merdinger

Univ. of PaisleyK.M. Spohr

RFD at EB IV: electronics

Application of RFD and other ancillary detectors for advanced ?-ray spectroscopy with GASP arrayPrinciple of operationRecoil Filter Detector at EB IVAdvantage and difficultyIndividual RFD elementEUROBALL IV & Recoil Filter DetectorFiltering of heavy recoilsPredictions for lighter recoilsExperimental energy resolutionSelection of exit channel:RFDLifetime estimationExample: terminating state in 44ScSelection of exit channel:RFD - EUCLIDESExample: SD band in 61CuPartial summaryRFD at GASPRFD at GASPDevelopment and perspectivesRFD at EB IV: electronics