roger caballero folch, frs user meeting 2011 - gsi, 28 th november 2011 s410 experiment gsi –...
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ROGER CABALLERO FOLCH,
FRS User meeting 2011 - GSI, 28th November 2011
S410 EXPERIMENT GSI – SEPTEMBER 2011
Introduction and astrophysics motivation
Setup: FRS – SIMBA – BELEN
Current analysis status and its outlook
Contents
1/14
Analysis Future goalsIntroduction Setup
Summary and future goals
Experiment
2/14
S410: Beta-decay measurements of new isotopes near the third r-process peak (N~126)
- Performed at GSI in September 2011 with a week of beam time
- Shared setup with S323 experiment
The measurements settings were
centered on two isotopes: 215Tl, 211Hg.
We have preliminarily identified the
following nuclei:
207-214Hg 205-210Au
203,206Pt 199,202Ir
211-217Tl
Analysis Future goalsIntroduction SetupIntroduction
Motivation
3/14
Nuclear structure knowledge: beta decay studies of these nuclei
provide information about their decay mechanism and nuclear structure in this mass region
Half lives (T1/2)
Beta delayed neutron emission probabilities (Pn)
Astrophysics (r-process): nucleosynthesis aspects of the heavy mass
elements. The new values for T1/2 and Pn, will provide valuable information
for the test of theoretical models.
Analysis Future goalsIntroduction SetupIntroduction
“Ignorance”-Curve
Exp. T. Kurtukian et al.Phys. Lett. B (Submitted)
DF3 + QRPA
+ FRDM + QRPA(P.Moeller, et al. 2003)
(I.Borzov, et al. 2003)
State of the art
4/14
Analysis Future goalsIntroduction Setup
N=126
t1/2 exists identifiedArea of interestPn (%) QRPABn= 2-3 MeV
Centered
Introduction
Analysis Future goalsIntroduction Setup
5/14
Setup
Fragment separator spectrometer (FRS). Beam characteristics.
SIMBA +BELEN
1.6 g/cm2 Be target
2x109 ions/spill intensity
Bρ settings for: 215Tl, 211Hg and as references 216Po, 205Bi, 135Sb
Spill length ~1s with a period around 4s
Separation in flightBρ – ΔE – Bρ
Introduction
Experimental hall (S4) configuration and settings
6/14TPC
MUSIC
SLITS
SCI
DEGRADER
ITAG SIMBA &BELEN
Analysis Future goalsIntroduction SetupSetup
Implantation detector: SIMBA (Silicon Implantation Detector and Beta Absorber)
7/14
SIMBA detector
Multilayer silicon detector
Allows to measure both ion implants and
β-decays.
Decay events can be correlated in time
with the detection of neutrons.
2 SSSD (7 segm.) 60x40 mm2 (1mm thick)
XY FRONT A B C REAR
Tracking layers XY (60 segm.) 60x60 mm2 (0.3mm thick)2 SSSD (7 segm.) 60x40 mm2 (1mm thick)3 DSSD (implantation area, 60x40 segm.): 60x40 mm2 (0.7mm thick)
Front view
Analysis Future goalsIntroduction SetupSetup
8/14
Neutron detector: BELEN (Beta Delayed Neutron Detector)
- Neutron detector designed by UPC GRETER research group (Barcelona)
- The detection of the neutron is based on the detection of products of the reaction
of the neutron with 3He counters: 3He + n 3H + 1H + 765 keV
Ion beam
n
n
n
Polyethylenemoderator
Proportional 3He counterSilicon
β decay detector
- 30 3He counters:
Analysis Future goalsIntroduction SetupSetup
8/14
Neutron detector: BELEN (Beta Delayed Neutron Detector)
BELEN-30 neutron detector
· 10 with 10 atm pressure
· 20 with 20 atm pressure
Neutron shielding
SIMBA inside the matrix
BEAMLINE
Analysis Future goalsIntroduction SetupSetup
Analysis Future goalsIntroduction Setup
Analysis procedure (Preliminary plots / ongoing)
9/14
Analysis Setup
Tracking detectors calibrations & particle ID
Particle ID check via 205Bi isomers,216Po α-decays
SIMBA calibrationimplantation patterns
Analysis of half lives and Pn
Digital data acquisition system features
A/Q
BiPbTl
HgAu
Pt
Po
215Tl
FRS setting 215Tl
SCI21-SCI41 ToF
TPC21-22 – TPC41-42 Position calibration
MUSIC 41-42-43 Energy Loss calibration
PRELIMIN
ARY
Analysis Future goalsIntroduction Setup
9/14
Analysis
Tracking detectors calibrations & particle ID
Particle ID check via 205Bi isomers,216Po α-decays
SIMBA calibrationimplantation patterns
Analysis of half lives and Pn
Digital data acquisition system features
BiPb
TlHg
AuPt
Po
Ir
Analysis procedure (Preliminary plots / ongoing)
SCI21-SCI41 ToF
TPC21-22 – TPC41-42 Position calibration
MUSIC 41-42-43 Energy Loss calibration
FRS setting 211Hg
A/Q
211HgPRELIM
INARY
10/14
Analysis Future goalsIntroduction Setup Analysis
Tracking detectors calibrations & particle ID
Particle ID check via 205Bi isomers,216Po α-decays
SIMBA calibrationimplantation patterns
Analysis of half lives and Pn
Digital data acquisition system features
205Bi setting has been used as Z identification
reference via isomer gamma rays and 216Po setting
as A/Q checking in the region of interest.
Analysis procedure (Preliminary plots / ongoing)
A/Q
Z
205Bi
keV
Cou
nts
11/14
Analysis Future goalsIntroduction Setup Analysis
Tracking detectors calibrations & particle ID
Particle ID check via 205Bi isomers,216Po α-decays
SIMBA calibrationimplantation patterns
Analysis of half lives and Pn
Digital data acquisition system features
Implants keV
Ch
Bet
a di
sint
egra
tion
s
- SIMBA calibrations are being performed with a 137Cs source
- β- decay curves will provide half lives values
ImplantationCo
un
ts
Energy deposited (ch)
Noise
Beta decay
Analysis procedure (Preliminary plots / ongoing)
- Time correlation between neutron and beta decay
-252Cf for BELEN efficiency and can be checked with
135Sb
12/14
Analysis Future goalsIntroduction Setup Analysis
Tracking detectors calibrations & particle ID
Particle ID check via 205Bi isomers,216Po α-decays
SIMBA calibrationimplantation patterns
Analysis of half lives and Pn
Digital data acquisition system features
N
NP n
nn
1
Pulser
Noise Neutron signal
Cou
nts
Energy (ch)
Analysis procedure (Preliminary plots / ongoing)
DDAS- Triggerless digital data acquisition system used for the first time in thistype of experiments at GSI.
- It allows to eliminate the dead timeof conventional acquisition systemsthanks to the double memory digitalcards which allow to acquire data and reading of previously taken data at the same time.
- Advantages:1. Increase the efficiency by about 8% (from 27 to 35%)2. Flexibility for large time correlation (fundamental to
obtain correlations with all neutron and to change the gates offline)
3. Allows to correct some experimental effects, e.g. To reduce neutron background from uncorrelated neutrons.
13/14
Analysis Future goalsIntroduction Setup Analysis
Tracking detectors calibrations & particle ID
Particle ID check via 205Bi isomers,216Po α-decays
SIMBA calibrationimplantation patterns
Analysis of half lives and Pn
Digital data acquisition system features
Analysis procedure (Preliminary plots / ongoing)
Outlook
14/14
Analysis Future goalsIntroduction Setup Future goalsAnalysis
Improved ID-Plot via final calibrations of frs detectors
Determine implantation rates for each identified isotope
Determine implant-beta correlations and neutron-beta correlations
Implement an analysis method for deriving half-lifes and for determining beta-delayed
neutron emission probabilities.
In collaboration with theoreticians, study the impact of these results on nuclear
models, as well as on r-process nucleosynthesis calculations.
Future goals
Upgrade of detector: up to 90 counters (detection efficiency ~70%): collaboration with Dubna
Combine with AIDA implantation detector (first separate tests in August 2011): talk Robert
Page (Tue, 10:10)
Optimize detection system (BELEN) and its acquisition (DDAS) for future experiments with
more exotic beams (FAIR).
Prepare for first experiments closer to the r-process path @FAIR/DESPEC (>2018)
Measure Pxn
The end!
Thanks to collaborators:
Institut de Física Corpuscular de València (IFIC)
Universitat Politècnica de Catalunya (UPC)
Helmholtzzentrum für Schwerionenforschung GmbH (GSI)
NSCL, Michigan State University (MSU-USA)
CIEMAT (Madrid)
Universidade de Santigo de Compostela (USC)
Department of Physics, University of Surrey (UK)
CFNUL Universidade de Lisboa (Portugal)
School of Physics & Astronomy, U. Edinburgh (UK)
Department of Physics, University of Liverpool (UK)
STFC, Daresbury Laboratory (UK)
Laboratori Nazionali di Legnaro, INFN (Italy)
Flerov Laboratory, JINR, Dubna (Russia)
CENBG, Université Bordeaux (France)
State of the art
4/16
Analysis status Data analysisIntroduction Setup Outlook & futureIntroduction
Effect of half-lives
The Astr. Jour., 579 (2002), H. Schatz et al.
Proc. CGS-13 (2009), G. Martinez-Pinedo
“Ignorance”-Curve
Focus of present proposal
r-path
State of the art
4/14
Analysis Future goalsIntroduction SetupIntroduction
FRDM + QRPA
K.-L. Kratz, (private communication)
r-proce
ss path
T1/2
Pn
Exp. T. Kurtukian et al.Phys. Lett. B (Submitted)
DF3 + QRPA + FRDM + QRPA(P.Moeller, et al. 2003)(I.Borzov, et al. 2003)
Effect of half-lives
The Astr. Jour., 579 (2002), H. Schatz et al.
Proc. CGS-13 (2009), G. Martinez-Pinedo
K.-L. Kratz, (private communication)
Particle identification
9/16
Analysis status Data analysisIntroduction Setup Outlook & futureAnalysis status
The method is based in Time of Flight (ToF) measurement according to the
energy loss (ΔE) in the (MUSIC) ionisation chambers and the B fields (Bρ) set.
205Bi setting has been used as Z identification reference via isomer gamma
rays and 216Po setting as A/Q checking in the region of interest.
A/Q
Z
205Bi
keV
Cou
nts
Setup
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