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Peter Kammel for the MuSun Collaboration. Muon Capture on the Deuteron The MuSun Experiment. BV39, Feb 21, 08. Collaboration. - PowerPoint PPT Presentation
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1
Peter Kammel
for the MuSun Collaboration
Muon Capture on the Deuteron Muon Capture on the Deuteron The MuSun ExperimentThe MuSun Experiment
BV39, Feb 21, 08
2
CollaborationCollaboration
V.A. Andreev, V.A. Ganzha, P.A. Kravtsov, A.G. Krivshich, E.M. Maev, O.E. Maev, G.E. Petrov,
G.N. Schapkin, G.G. Semenchuk, M.A. Soroka, A.A. Vasilyev, A.A. Vorobyov, M.E. Vznuzdaev Petersburg Nuclear Physics Institute, Gatchina 188350, Russia D.W. Hertzog, P. Kammel, B. Kiburg, S. Knaack, F. Mulhauser, P. Winter
University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA M. Hildebrandt, B. Lauss, C. Petitjean
Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland T. Gorringe, V. Tishchenko
University of Kentucky, Lexington, KY 40506, USA R.M. Carey, K.R. Lynch
Boston University, Boston, MA 02215, USA R. Prieels
Universite Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium F.E. Gray
Regis University, Denver, CO 80221, USA A. Gardestig, K. Kubodera, F. Myhrer
University of South Carolina, Columbia, SC 29208, USA
Combined forces MuCap & MuLan
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Goal and MotivationGoal and Motivation
+ d + d + n + n + n + n RateRate dd from from d(d() atom) atom
MeasureMeasure dd to < 1.5 %to < 1.5 %
Simplest weak interaction process in a nucleusSimplest weak interaction process in a nucleusallowing for precise theory & experiment allowing for precise theory & experiment
nucleon FF (gnucleon FF (gPP) from MuCap) from MuCap
model-independentmodel-independent calculations with effective field theorycalculations with effective field theory
Close relation to neutrino/astrophysicsClose relation to neutrino/astrophysics model-independent connection model-independent connection +d+d to pp fusion and to pp fusion and +d +d
reaction reaction
Broader Impact on modern nuclear physicsBroader Impact on modern nuclear physics
EFT relates EFT relates +d+d to strong processes like to strong processes like +d +d + n +n, a + n +n, annnn
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+ d + d + n + n + n + n TheoryTheoryAxial current reaction
Gamow-Teller 3S1 1S0
one-body currents well definedFF, deuteron wavefunction, ann
two-body currents not well constrained by theory (short distance physics)
Methods• Potential model + MEC
• Effective field theories (EFT) pion less (q/m)
ChPT(q/)
• hybrid EFT (EFT operators, Pot.Model wavefct)
MEC
L1A, dR
EFT
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+ d Experiment+ d Experiment Experimental Challenges
Dalitz Plot
Intensity at low Enn
ChPT covers most of DP
EFT only p< 90 MeV/c
→ e= 455162 s-1
dq,d → n+n+ q ~ 10 s-1, d = 400 s-1
d() + d→ d() + d
dd → 3He + n + rates ~
d
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Precise Experiment NeededPrecise Experiment Needed
Potential Model + MEC
pionless, needs L1A
hybrid EFT
consistent ChPT
Determine L1A from clean system
Ramnifications for -astro physics
Quantify consistency of hybrid approach
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Basic solar fusion reaction
p + p d + e+ + Key reactions for Sudbury Neutrino Observatory
e + d p + p + e- (CC)
x + d p + n + x (NC)
Intense theoretical studies, scarce direct data
EFT connection to +d capture via LEC L1A, dR
Muon capture soft enough to relate to solar reactions
Connection to Neutrino/AstrophysicsConnection to Neutrino/Astrophysics
with L1A ~ 6 fm3
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Quest for LQuest for L1A1A, d, dRR
Precision +d experiment by far the best determination
of L1A in the theoretically clean
2-N system
“Calibrate the Sun”
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Muon Capture, Big PictureMuon Capture, Big Picture
+ p
+ d + 3He
{ gP, gA, ChPT }
{ gP, gA, ChPT, L1A, ann } { gP, gA, hybrid EFT, L1A, 3N}
Final MuCap 2-3x improvement
Combinedanalysis
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Experimental StrategyExperimental Strategy
Two main conditions
Unambiguous physics interpretation
Muon kinetics optimization of D2 conditions
Very high precision d to 1.2% (5 s-1)Statistics: several 1010 events
Systematics !
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Muon KineticsMuon Kinetics
Collisional processes density dependent, e.g.
hfs transition rate from q to d state = qd
density normalized to LH2 density
complicated, can one extract fundamental weak parameters ?
Muon-catalyzed Fusion
q
d
qd
q
d
qd
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Optimize Muon KineticsOptimize Muon Kinetics Time Distributions
Sensitivities (d 1%, x 2 x)
d()d()
He
d MuCap MuSun
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Use Basic MuCap TechniqueUse Basic MuCap Technique Lifetime method
1010 →e decays measure to 10ppm,
d = 1/ - 1/to 1%
Unambiguous interpretation
at optimized target conditions
Ultra-pure gas system and purity monitoring at 1 ppb level
Clean stop definition in active target (TPC)
3 times higher rate with Muon-On-Request (MuLan)
log
(co
un
ts)
te-t
μ+
μ –
d reduce
s lifetime by 10-3
→ e
MuCapTPCtop
TPCside
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Experiment OverviewExperiment Overview
PC
SC
ePC2
ePC1
eSC
Cryo-TPC
e
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ObservablesObservables Observables in MuSun experiment
• decay electrons main observable
• fusion and capture essential as kinetics and background monitors
Experience from MCF experiments
N capture
1.8 1010
109
5 105
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Cryo-TPC Design CriteriaCryo-TPC Design Criteria Recombination Drift Velocity
Equation of State Specs
0
2
4
6
8
10
12
24 26 28 30 32 34 36
T (K)
p(b
ar)
SVP
10% LH25% LH2
2.5% LH27.5% LH2
liquid
gas
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Cryo-TPC DesignCryo-TPC Design
Aluminum shell
Rear neon collector
Front neon collector
Be window flange Be window
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Technical Design Cryo-SystemTechnical Design Cryo-System
Vibration free cooling
Continuous cleaning
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Detectors and DAQDetectors and DAQ Cryo-TPC special
Other detectors/infrastructure from MuCap
detectors as impurity monitor
DAQ from MuCap/MuLan
new: full analog TPC readout (complicated energy spectrum)
• 10x10 pads• two 8-bit waveform digitizer
channels per pad (50 MHz)• 15 MB/s (4 MHz/s) before
lossless compression
2006
BU digitizer
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Statistics + SystematicsStatistics + Systematicsd (Hz)
- Statistics 3.4
Systematics 3.3
+ from MuLan 0.455
total d uncertainty 4.8 Hz
1.2 % d
10.5 ppm
1.81010 events
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Pad Optimization in ProgressPad Optimization in Progress Muon stop parameters
Fake stops by +p scattering
Fusion interference
GEANT 10x10 pad
MuCap TPC
GEANT
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Gas PurityGas Purity
Circulating Hydrogen Ultrahigh Purification System (CHUPS)
US CRDF 2002, 2005
New: • cryo-TPC
• cryo filter before TPC
• continuous getter in gas flow for gas chromatography
Particle detection in TPC
much harder – fusionfor MuSun – signal 1 MeV
• excellent TPC resolution
• full analog readout
• tags – p after capture
– X-ray
• protium measurement
Rare impurity capture: d + Z d + Z (Z-1)* +
MuCap achieved: ~ 10 ppb purity and 0.1 ppb purity monitoring
MuSun needs: ~ 1 ppb purity or 0.5 ppb purity monitoring
(Z-1)* +
23
Measuring ProgramMeasuring Program Stage 1 – 300 K TPC
• Rebuild (spare) MuCap TPC as ionization chamber
• Energy resolution
• Identification and separation of fusion recoils
• Full analog readout
• Measure d → Z transfer rate
• Optimize N capture monitor with dedicated setup
Stage 2 – Cryo-TPC
? 6Ready Fall 08Ready Fall 09
2-3 runs
in total (prep. and data taking) 4 years
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Responsibilities & BudgetResponsibilities & Budget
Budget estimates
Total new equipment 350k CHF
Annual running costs 100k CHF
Heavily based on larger investments made for MuCap/MuLan
Already positive response from main funding agenciesNational Science Foundation, USA
Russian Academy of Sciences, Russia
Full funding requests to agencies after PAC approval