is the science compelling? is fermilab the right place? is the experiment well designed?
DESCRIPTION
e. Momentum Spin. A proposal to measure the muon anomalous magnetic moment to 0.14 ppm precision The New g-2 Collaboration. Is the science compelling? Is Fermilab the right place? Is the experiment well designed? Is it cost effective?. - PowerPoint PPT PresentationTRANSCRIPT
A proposal to measure the muon anomalous magnetic moment to 0.14 ppm precision The New g-2 Collaboration
Is the science compelling? Is Fermilab the right place? Is the experiment well designed? Is it cost effective?
Momentum
Spin
e
D. Hertzog and L. Roberts – PAC Fermilab – March 6, 2009
Built on the foundation of E821, with important new strength added
@ 20 Institutions
a
List does not include the many PDRAs and Students who will join an approved effort
a = (g – 2)/2 is non-zero because of virtual loops, which can be calculated very precisely
B
QED
Z
Weak Had LbL
Had VP
Had VP
Known well Theoretical work ongoing
a = 51 x 10-11
arXiv:0809.3085 Eduardo De Rafael (CPT)
Present Status: Experimental uncertainty = 63 x 10-11 (0.54 ppm)
0.46 ppm statistical 0.28 ppm systematic
Theory uncertainty = 51 x 10-11 (0.44 ppm)
Where we are and where we are going
Leads to a(Expt – Thy) = 295 ± 81 x 10-11 3.6
Limit was counts
Expected situation after experiment: Experimental uncertainty: 63 16 x 10-11
0.1 ppm statistical 21x the E821 events 0.1 ppm systematic overall
0.07 ppm field 0.17 0.07 0.07 ppm a 0.21 0.07
Theory uncertainty: 51 30 x 10-11
(If xx remains 295, the deviation from zero would be close to 9)
Future: a(Expt – Thy) = xx ± 34 x 10-11
Precise knowledge of a will aid in discrimination between a wide variety of standard model extensions
UED models (1D) typically predict “tiny” effects Incompatible with a a of ~ 300 x 10-11
SUSY models – there are many – predict a contributions of about the observed magnitude for a
These are rather well studied, so we will consider a few cases
The “Uninvented” – perhaps most importantly, sets a stringent experimental constraint for any new models
SUSY: Muon g-2 is very sensitive through loops, which are amplified by tan
See full Topical Review: D. Stöckinger J.Phys. G34 (2007) R45-R92
2
SUSY -11μ
SUSY
100 GeVa ≈130×10 tanβ sign μM
Difficult to obtain at the LHC
The Snowmass Points and Slopes are 10 representative SUSY models with typical parameters for MSUSY masses and tan, etc. They serve as test points to indicate the discrimination power of experiments.
Muon g-2 is a powerful discriminator no matter where the final value lands
SPSDefinitions
Universal Extra Dimensions 1D
Illustration of “resolving power”
among SUSY models
Model
UED
Future?
PresentPresent
Models
Suppose the MSSM reference point SPS1a* is realized and parameters are determined by global fit from full LHC data
sign() difficult to obtain from the collider tan poorly determined by collider
* SPS1a is a ``Typical '' mSUGRA point with intermediate tan = 10
LHC (Sfitter)
Old g-2
New g-2
g-2 is complementary to the LHC
Connection between a, EDM and the charged Lepton Flavor Violating transition moment → e
→ e a (real) EDM (imaginary)
SUSY slepton mixing
The keys to an improved precision experiment are: more stored muons and reduced systematic errors
Build on a proven formula E821 studies to improve at BNL, J-PARC, or FNAL P989
Many studies completed, much documentation Shovel-ready experiment
Why Fermilab is uniquely appropriate Aligned with laboratory direction toward Intensity Frontier
For example, synergistic with Mu2e Runs parasitically with Main-Injector neutrinos
Efficient use of facility Proton intensity and beam structure ideal for required statistics
1.8 x 1011 events in final fits Reduced hadronic-induced background at injection
Long decay beamline is key to reducing many systematic errors Increased fill frequency reduces instantaneous rate
x4 at FNAL compared to BNL
(1) Precession frequency
(2) Muon distribution
(3) Magnetic field map
The measurement involves determining 3 quantities to high precision
B
g 2
1 2 3
TIME
Double Blind Analysis
a
A consistent set of measurements with a steady improvement in precision.
4 key elements of the g-2 measurement
1. Polarized muonsforward decays, captured in FODO, ~97% polarized source
2. Precession proportional to (g-2)
3. P magic momentum = 3.094 GeV/cE field doesn’t affect muon spin when = 29.3
4. Parity violation in the decay gives average spin direction
µ
EaBa
mce
a
1
12
ee
2
2a spin cyclotron
g eB
mc
Booster/Linac
Extraction from RR
Injection to RR
NEW TRANSFER LINE
A3 lineA2 line
Main Injector
F0P1 line
MI-52
MI-30
p
Recycler
_p
MI-10
Pbar
AP0
P2 line
Accelerator Overview
INJ8GeV
Polarized muons delivered and stored in the ring at the magic momentum, 3.094 GeV/c
Uses 6/20 batches* parasitic to program
Proton plan up to AP0 target is almost the same as for Mu2e
Uses the same target and lens as the present p-bar program
Modified AP2 line (+ quads) New beam stub into ring Needs simple building near
cryo services*Can use all 20 if MI program is off
The 900-m long decay beam reduces the pion “flash” by x20 and leads to 6 – 12 times more stored muons per proton (compared to BNL)
Stored Muons / POT
Flash compared to BNL
parameter FNAL/BNL
p / fill 0.25
/ p 0.4
survive to ring 0.01
at magic P 50
Net 0.05
The Storage Ring exists and will be moved to FNAL
incoming muons
Quads
Power supplies
Quads
Vacuum system
Fiber harps
Kickers
Into the ring Beamline “stub”
Design for FNAL
Open-end inflector*x2 increase in transmission
Kicker deflects beam onto orbitImprovements planned for pulse shape / magnitude
AP-3
Existing Proposed
*This was built at one-third length, tested, but final design had closed ends
stub
An “event” is an isolated electron above a threshold.
e+
2.5 ns samples
N
A
NA2
<A>=0.4
An “event” is an isolated electron above a threshold.
e+
2.5 ns samples
Segmenting detectors will reduce pileup. New W-SciFi calorimeter built and tested (and published)
20-fold segmentation for PMTs 0.7 cm X0
10% resolution at 2 GeV R&D option, 35-fold segmentation
using onboard SiPM
Low E
High E
Traditional method of determining a is to plot Number vs. Time
Event Method
Geant simulation using new detector schemes
N
A
NA2
<A>=0.4
Here, Asym is the average asymmetry of events above energy threshold cut
A complementary (integrating) method of determining a is to plot Energy vs. Time
Event Method
Geant simulation using new detector schemes
Energy Method
Same GEANT simulationPotential method for Project X rates
The magnet will be carefully shimmed and precisely mapped
Continuously monitored using 366 fixed probes mounted above and below the storage region
Measured in situ using an NMR trolley
1 ppm contours ppm
0.05
0.09
0.05
0.07
0.10
0.17
(Final BNL)
g-2 budget estimate, contingencies included(assumed protons are delivered to AP0 at 15 Hz operation of booster)
Ring relocation
NSF Nucl.+ International
Relatively standard beamline elements
Mu2e & g-2common
g-2 & Mu2e need RF
PROTONs
Technically driven schedule 2009
PAC presentation / Stage-1 approval Some R&D funds made available
Year 0 Planning / designs / technical reviews
Year 1 Building started key driver for timeline Modifications of proton complex Pack and move ring and other items from BNL Detector, electronics tests and pre-construction Re-machine fixed probe locations on vacuum chambers
Year 2 Install and assemble ring at FNAL Complete modifications of beamlines related to g-2 Special rate tests of pion / muon flux at key test points Detector, electronics production
Year 3 Complete ring construction and commission Shim magnet (9 mo) Calibrations of detectors, integrate counting room, DAQ
Year 4 Physics commissioning Start real data taking
A fairly uniform flow of funds is required … no big “spike” for any single purchase
Immediate R&D tasks Lithium lens at 18 Hz
Test lithium lens for 18 Hz operation at the reduced power for 3.1 GeV/c beam
Decay channel and stored muon simulations Complete end-to-end beam simulation to make the most complete
and cost-effective choices for Optimization of the beam focus on the target and Li lens optics Addition of quads for AP2 beam line and transport efficiency thru AP-3 Design of beamline stub into ring Storage ring acceptance versus kicker performance
Half-length kicker plate test Reduced inductance is key to shorter pulse of greater magnitude;
carry out test with a half-length kicker in lab on existing setup Fixed probe re-positioning
Re-optimize fixed probe locations to increase the number of working fixed probes
Large-scale W/SciFi prototype with SiPM readout Full-scale prototype; PMT and SiPM readout.
In-vacuum straw chambers for EDM and traceback A test setup is underway now at FNAL to investigate this concept.
Summary
Unique physics opportunity with decades-long track record of being important and influential to our field, including > 1400 citations (170 in 2008)
Will provide important constraints on the interpretation of any new physics found at the LHC or elsewhere
Window of opportunity after Tevatron completion and before the major Mu2e and DUSEL projects take center stage – Our request is 4 x 1020 POT
Great return on investment, given the impact and the natural alignment with FNAL’s future
Possible topics for further discussion Theory
Current / future status of Hadronic Vacuum Polarization Current / future status Hadronic Light-by-Light What are the SPS points? CMSSM Constraints? Show us more about the Sfitter results w/wo g-2 How general is the UED “tiny effects” prediction?
Technique More on a parasitic EDM measurement a systematic errors Why a longer beamline? What drives the detector choice? Magnetic field shimming and monitoring What was used to calculate the beamline rate? How was the event rate obtained? What is involved in moving the ring?
Other More on yellow “proton complex” budget box What about JPARC?
D. Hertzog and L. Roberts – PAC Fermilab – March 6, 2009
Analyticity and the optical theorem: Back
contributionerror2
(from F. Jegerlehner)
• Future efforts will reduce errors– Additional KLOE data (in hand, near term)– CMD3 at VEPP2000, up to 2.0 GeV (next 5 years)– perhaps Belle
|F|2 from KLOE, CMD2 and SND agree well Back
weighted contribution
recall that:
Suppose the hadronic contribution increased to remove the difference?
• A similar dispersion integral enters elsewhere
• Increasing (s) to remove the (g-2) difference lowers the Higgs mass limit PRD 78, 013009 (2008)
• This cross section is important for a and for any precision EW physics.
• Future work continues in Frascati and Novosibirsk. Belle is also beginning to explore this possibility.
Back
Note, with a = 295 x 10-11 … If HLBL is the source of the difference with SM, it would need to increase by 11 ....
Back
arXiv:0901.0306v1
Dynamical models with QCD behavior
The 0 (Goldstone) contribution fixes sign of the contribution From pt and large Nc QCD
The magnitude of the HLBL is about the same as the magnitude of the 3-loop HVP which can be calculated from the dispersion relation.
It’s hard to believe that the HLBL would be huge compared to the other 3-loop contributions.
Examples of other 3-loop hadronic contributions:
Back
How general is the UED “tiny effects” prediction?
UED models (1D) typically predict “tiny” effects Incompatible with a a of ~ 300 x 10-11
The statement refers to the UED models originally proposed and studied by Appelquist, Cheng, and Dobrescu, and also by Rizzo in 2000/2001. The results for g-2 in the UED models with one extra dimension is (according to these references) below 50 x 10-11 as written in our proposal.
While there might be modified UED models with larger contributions to g-2, this again demonstrates that g-2 is very powerful tool to discriminate between different new physics models. (D. Stockinger)
Back
Sfitter LHC global fit(Alexander, Kreiss, Lafaye, Plehn, Rauch, Zerwas; Les Houches 2007, Physics at TeV Colliders)
With g-2, many are improved, some significantly
Result for the general MSSM parameter determination at the LHC in SPS1a. Flat theory errors (non-gaussian) are assumed. The fit is done with and without inclusion of the current measurement of g-2.
Confirmation of tanbeta
measurement by comprehensive
global fit.
Improvement of tanbeta-error with
current g-2:
4.5 -> 2.0
estimated improvement with
future g-2:
4.5 -> 1.0
Back
SPS points and slopes SPS 1a: ``Typical '' mSUGRA point with intermediate value of tan_beta. SPS 1b: ``Typical '' mSUGRA point with relatively high tan_beta; tau-
rich neutralino and chargino decays. SPS 2: ``Focus point '' scenario in mSUGRA; relatively heavy squarks
and sleptons, charginos and neutralinos are fairly light; the gluino is lighter than the squarks
SPS 3: mSUGRA scenario with model line into ``co-annihilation region''; very small slepton-neutralino mass difference
SPS 4: mSUGRA scenario with large tan_beta; the couplings of A, H to b quarks and taus as well as the coupling of the charged Higgs to top and bottom are significantly enhanced in this scenario, resulting in particular in large associated production cross sections for the heavy Higgs bosons
SPS 5: mSUGRA scenario with relatively light scalar top quark; relatively low tan_beta
SPS 6: mSUGRA-like scenario with non-unified gaugino masses SPS 7: GMSB scenario with stau NLSP SPS 8: GMSB scenario with neutralino NLSP SPS 9: AMSB scenario
www.ippp.dur.ac.uk/~georg/sps/sps.htmlSPS PLOT
Back
Parasitic Muon EDM Measurement using straw tube arrays
The EDM tips the precession plane, producing an up-down oscillation with time (out of phase with a)
Measure upward-going vs. downward-going decay electrons vs. time with straw tube arrays
E821 straw-tube array
BackarXiv:0811.1207v1
E821 Data: up-going/down-going tracks vs. time, (modulo the g-2 frequency):
BNL traceback measurement was entirely statistics limited 1 station Late turn-on time Small acceptance Ran 2 out of 3 years
(g-2) signal: # Tracks vs time, modulo g-2 period, in phase.
EDM Signal: Average vertical angle modulo g-2 period. Out-of-phase by 90° from g-2; this is the EDM signal
Back
(g-2) EDM
The new idea imagines in-vacuum straws, matched with out-of-vacuum pre-calorimeter straws (used also for shower impact)
We are already studying at FNAL, in-vacuum straw chambers for “traceback” systems on many of the stations, which will serve as EDM measurement stations as well
Out-of-vacuum straws / impact detector
Back
How was event rate obtained?
Proton complex parameters and plans
Compared to achieved BNL stored muon per proton rate and detailed factors for beamline differences
Monte Carlo and simple calculations
This is the key factor. We have calculated 11.5 so far, so we have included a “100% contingency” in estimating the beam time request to allow for something to go wrong.
MARS15 model of target, beamline simulation to capture / decay pions
Back
The Precision Field: Systematic errors
• Why is the error 0.11 ppm?– That’s with existing knowledge and experience
• with R&D defined in proposal, it will get better
Back
Next
(g-2)
a Systematic Error SummaryBack
What drives the detector choice? Compact based on fixed space Non-magnetic to avoid field
perturbations Resolution is not critical for a
Useful for pileup & gain monitoring E821 “8%”; We propose 10% for
tungsten-based calorimeter Pileup depends on signal speed and
shower separation 4/5 events separated was goal GEANT sim work in good shape
Many more details and studies available. See also,
Back
Conceptual idea for Si-PM readout of W/SciFi modules
Si PM Array W / SciFi BlockWinston cone Bundle fibers
Back
3 cm
Benefits of a longer beamline
Reduced pions Permits “forward” decays Collects “all” muons Eliminates “lost muon” systematic from muons born
just prior to the ring
Back
Ring relocation
Heavy-lift helicopters bring coils to a barge Rest of magnet is a “kit” that can be trucked to and from the barge
Back
The “yellow” budget box is related to accelerator improvements for the intensity frontier in general
Assumed done
Must do for Mu2e, g-2 and any other expt.
see below
Recycler Ring RF For g-2: makes 4 mini bunches out of each Booster
injection. Each is then extracted for g-2 as a whole to strike the target and create a pion/muon bunch
With value engineering, this cost could go down
Back
Extraction Recycler to P1
P5 suggested we “determine the optimal path toward a next generation experiment” by examining JPARC and FNAL
Feb. 2008 Technical note sent to P5 by collaboration outlining generic
comparisons (and some rough cost considerations) June 2008
2-day, joint Japan / US collaboration meeting held to examine technical possibilities at three labs (BNL, FNAL, JPARC).
Conclusions It is challenging to stage the “magic ” experiment at JPARC. Real
estate exists only for a short backward decay beamline. Need bunch splitting to achieve h = 90 to reduce pileup J-PARC regulations for cryogenics (probably) prohibit SC coil design
from E821 to be used. Coils would have to be rebuilt at J-PARC Single user mode only
Current thoughts for JPARC Use of low-momentum (non-magic ) ring being explored with
muons from 3-GeV Booster. The idea is in its infancy. Possible future focus on small ring dedicated EDM effort
Back
Beamline study – simplified
Up to proton batch in Recycler, same as Mu2e
RF in Recycler divides batch into 4 bunches of 1012 p/bunch
Pion production on existing target done with MARS15
Acceptance computed into AP-2 line using OptiM
Pi-to-Mu calculation and captured muons simulated with Decay Turtle for various scenarios of quad lattice spacing
The rest of the study is based on a detailed comparison to BNL where hard numbers exist and ratios are well understood
Back
66 ms of a “batch”
1 2 3 4
11 ms
OptiM
MARS15
Typical CMSSM 2D space showing g-2 effect(note: NOT an exclusion plot)
This CMSSM calculation: Ellis, Olive, Santoso, Spanos. Plot update: K. Olive
gaugino mass
scal
ar m
ass
Excluded for neutral dark matter
2
Present:a = 295 ± 88 x 10-11
Topical Review: D. Stöckinger hep-ph/0609168v1
Here, neutralino accounts for the WMAP implied dark matter density
Back
Typical CMSSM 2D space showing g-2 effect(note: NOT an exclusion plot)
This CMSSM calculation: Ellis, Olive, Santoso, Spanos. Plot update: K. Olive
gaugino mass
scal
ar m
ass
Excluded for neutral dark matter
With new experimental and theoretical precision and same a
Futurea = 295 ± 34 x 10-11
Topical Review: D. Stöckinger hep-ph/0609168v1
Here, neutralino accounts for the WMAP implied dark matter density
Historically muon (g-2) has played an important role in restricting models of new physics.
It provides constraints that are independent and complementary to high-energy experiments.
Back