Readiness Review for Jlab Experiment E04 - 007
description
Transcript of Readiness Review for Jlab Experiment E04 - 007
Readiness Review for Jlab Experiment E04 - 007
Hall A and BigBite Collaboration experimentApproved Jan 2004 for 16 days
Precision Measurement of the Electroproduction of 0 Near Threshold: A Test of Chiral QCD Dynamics
Co-spokespersons J. Annand, D. Higinbotham, R. Lindgren, V. Nelyubin, and B. Norum,
Physics Goal: Extract high precision data in a fine grid of Q2 and W from Q2 = 0.05 - 0.10in steps of 0.01 (GeV/c)2 and from W = 0 - 20 MeV above threshold in steps of 1 - 2 MeV.Complete kinematic coverage from 0 - 4 MeV above threshold for proton momentum > 220 MeV/c
€
• σ T + εLσ L 2 - 4 %
• σ LT 3- 6 %
• σ TT 10 - 20 %
€
H(e,e' p)π 0
Outline
•Overview•Beam Energy and Current•Beam Monitoring•Targets•Electron Arm Spectrometer•Proton Arm BigBite•Mechanical Hardware Additions•Calibrations•Run Plan/Commissioning•Production Running•Milestones•People Power•Safety
d 5σdΩe'dEe'dΩ
* =σ
σ =Γv (σ 0 +h 2εL 1−ε( )σ LT '(θ* )sinφ
* )
σ 0 =σ T(θ* ) + εLσ L (θ
* ) + 2εL 1+ ε( )σ LT (θ* )cosφ
* + εσTT (θ* )cos2φ
* )
θcone = 4.5o
W
(MeV)
Above
Threshold
Q2
(GeV/c) (Deg.)
1075 1.7 - 0.05 4.5
1076 2.7 - 0.10 4.5
1095 22 - 0.10 9
θcone
p
Vertical +/- 18 degHorizontal +/_ 5 deg
25 cm
80 cm
117
BigBite Solid Angle ~100msr
Proton Cone
Layout of Experiment in Hall ADetect electron in HRS and recoil proton in BigBite.
LH2
H (re, e'p) π0
Target• 20 cm Liquid Hydrogen( LH2)• 200-175 m 6061 Al
Luminosity• 1-2 x 1037 Hz/cm2
HRS
Electron
BigBite
BeamDump
HRSLuminosityMonitor
MWDC(12 Planes)p
E-E Trigger Scintillator Arrays
Energy 1.2 GeVCurrent 1- 2 A e
Beam Conditions
• Beam Energy 1.1 - 1.2 GeV–No higher than 1.2 GeV–Need the best energy resolution as possible < 2 x 10-4
–Energy lock on–ep/arc energy measurement and elastic scattering
• Beam Current –Production running 0.5 - 20 a–Rastered beam 2 mm x 4mm
• Polarization as high as possible• Beam Monitoring
–BCMs, BPMs, Silver calorimeter, Moller Polarimeter
• Pulsed beam - Investigate using to calibrate acceptance of BigBite in single arm mode. (Radiation tail method looks sufficient)
Targets
• Cryo-targets liquid hydrogen– Two different length targets will help disentangle systematic errors.– A 20 cm long, 2 cm wide/hign 200 um thick window thick aluminum cell
exist.• Production data will be taken on the 20 cm cell.• Investigating shielding BB from windows of cell at one kinematics. .• Compare to data with software cuts on z position .
– A 4 cm pan cake cell with thin Be window will be used for same kinematics above.
• Small target. Smaller acceptance corrections. Take data on empty cell for background. Can not correct in software.
• Compare with data above for same kinematics.
• Multi-foil C12 target, C, Ta ,BeO– Solid Target for elastic energy and z position measurements.
Targets
Electron Arm Spectrometer
• Range of electron angles for production running and acceptance calibration– Angular range 12 .5 to 80 degrees – Momentum range [GeV/c] 0.3 to 1.2 GeV/c
– VDC1 Yes
– VDC2 Yes
– S1 Yes
– S2 Yes
• Only need to cover about 20 MeV in focal Plane.• Excellent intrinsic resolution in W and and Q2
• Rates are high due to radiation tail in the region of pion threshold.• Need to turn off high voltages for PMTs outside this range of W• Air coupling. Contributes to somewhat degraded energy resolution in W.
– Still sufficient to accomplish Physics goal• Investigating using smaller and thinner window 10 by 6 cm window for HRS with snout.
Q Squared vrs Electron Angle for Old and New set of Beam Energies
00.010.020.030.040.050.060.070.080.09
0.10.110.120.130.140.150.160.170.18
0 5 10 15 20
Electron Angle
Q (GeV/c)
2
1200 MeV 12.5 Deg
2400 MeV 6.0 Deg
3200 MeV 6.0 Deg
1200 MeV 14.7 Deg
1200 MeV 16.6 Deg
Electron Rate In HRS
Proton Arm BigBite
Replace Havar with200 m aluminum(Old slide)
1200 Mev Beam ( pi0,p)
200
300
400
500
600
30 40 50 60 70
Proton Lab Angle (Deg.)
Proton Lab Momentum MeV/c
HRS 12.5 Deg
HRS 14.7 Deg
HRS 16.6 Deg
BigBite in-plane range
Proton Arm BigBite
• The low energy recoil protons will be detected in two of the MWDC chambers commissioned in the GEN Experiment. The Middle chamber will be upgraded at UVa.Three more planes will be added to bring it up to six planes. Mitra will discuss this.
• The MWDC are followed by two planes of 24 scintillators each. A 3 mm thick E plane and a 30 mm thick E plane. These were designed and tested by Glasgow and commissioned in the SRC experiment. They will be used for particle ID for protons and time of flight will be used to measure momentum of low momentum protons. Better than wire chambers at low p.
• The trigger for E07-004 will be a coincidence between the E plane and the HRS-L.
• The hadron package electronics, BigBite trigger for E04-007, readout, and milestones will be discussed by B. Moffit, Plan to use VME. Have Fast bus for back-up.
• Modifications to BigBite frame are being made to accommodate two wire chambers followed by E-E scintillator planes.
• Need to minimize straggling of low energy protons. Transport protons using helium a few mm above atmospheric pressure. Cheaper and more convenient than vacuum. Come back to this later.
Pi0 TRIGGER PLANE RATES20 cm LH2 Target 2 ua 1200 MeV beam
Scaled by a factor of 2.0 from SRC 3-10-05 Halog
0
200
400
600
800
1000
1200
1400
1600
1800
2000
1 3 5 7 9 11 13 15 17 19 21 23 25PMT Position
KHz
DEL
DER
EL
ER
• Scintillator Rates scaled from measured rates in SRC Experiment.
• Shows why we plan to use the E plane in the trigger and not the E. We may miss some low energy protons. Needs to be investigated.
3 mm E Plane
30 mm E Plane
• Machining of scattering chamber clamshell flange-right (CS-R) with windows for BigBite and HRS-R(Monitor).
• Machining of scattering chamber clamshell flange- left (CS-L)for HRS-L with windows for production data (12.5 - 16.6 Deg.) and elastic calibration data (40 - 80 Deg)
• “Coffee can” collimator, vacuum window, and flanges
• Construction of polyurethane “helium containment” balloons for BigBite and coupling to scattering chamber and wire chambers support stand.
• Helium gas handling system, pressure monitor, venting to outside Hall A.
New Mechanical Hardware Additions
Scattering chamber
Clamshell flange (not here yet)
“Coffee can” collimator
0.005” Polyurethane Balloon(sides only)
10 m Mylar Balloon
Front wire chamber
Upgraded Rear wire chamber
E Plane E Plane
20 H targetElectron Beam
10 m mylar foil
Coffee Can Collimator
Clamshell and Coffee Can CollimatorSide View
Clamshell and Coffee Can CollimatorTop view
Transport of low energy protons (200-600 MeV/c) from target through BigBite to MWDC
•Transport protons using helium a few mm above atmospheric pressure. Almost as good as using vacuum. More convenient and cheaper.
•Use company that makes polyurethane helium filled balloons of all shapes and sizes. Polyurethane skin 0.15 - 0.005 “ thick. Will lose helium slowly over a few days. Test leakage rate.
•Flexible enough to have limited angular movement of BigBite. Show sample material.
•Stretched over circular snout fixed to scattering chamber and hot glued
• Stretched over rectangular angle aluminum attached to wire chamber frame and hot glued
• Investigate stability of system and radiation damage of polyurethane and glue.
Shape of Polyurethane Helium Filled Balloon
206.2 cm
44.0 cm
33.1 cm
38.7 cm
Bottom view
2 Deg
5 cm
25.2 cm
18 Deg
18 Deg
Side view
122.9 cm
33.8 cm
157.8 cm
82.3 cm5 cm
Stretch over aluminum support frame and hot glue poly and terminate with 10 m mylar
Stretch over “coffeecan” collimator and hot glue
Test on Balloons
• Need to always keep inflated above atmospheric pressure• Monitor during the experiment. This is crucial.
• Mechanical stability of of joints and seams and leak rates• On the polyurethane balloons and mylar balloons• Conduct radiation damage test on both types.
– Effects on hot glue joints– Effects on seams– Effects on polyurethane
GEANT Results
Beam Energy
GeV
Transport
MediumHRS
Target Cell
Window
Vacuum
Window
σ Miss. Mass)
MeV
σ W)
MeV
σ c.
m.)
Deg.
σ Deg.
σ Q2(GeV/c)2
1.2He
bag
Air
Coupled
190 m
Al
170 m
Al
2.11.0
18.4 Ave
26 Ave 1.7x10-3
1.2He
bag
Vacuum
coupled
190 m
Al
170 m
Al2.0 1.0
Same as
above
Same as
above1.5 x 10-3
1.2He
bag
Air
Coupled
25 m
Havar
25 m
Havar2.0 1.0
15.9 ave
19.4 ave
1.2 x 10-3
2.4He
bagVacuum Coupled
25 m
Havar
25 m
Havar1.1 0.6 11 12.5 0.60x10-3
2.4Vacuum
Chamber
Vacuum
coupled
25 m
Havar
150 m
Kapton1.0 0.6 10 11.0 0.56x10-3
W = 1 - 4 MeVQ2 = - 0.048 to -0.07 (GeV/c)2
σp 2 σz 22 cmB=7 kG at 1.2 GeV
Q2=0.10 (GeV/c)2
Distler PRL 80, 2294 (1998)
LEC’sa3 = - 0.92 and a4 = - 0.99
Q2=0.05 (GeV/c)2
Merkel et al. PRL 88, 1230 (2002)
ChPT Bernard, et al. NP A607,379(1996)
MAID -----
• Large deviations between ChPT and data• Need data in a finer grid in Q2
Electro- 0 production on the protonσ t
ot
b
σ to
tb
Calibrations/Commissioning
• Beam Current integration - Silver Calorimeter
• BigBite angle and acceptance in-plane–Elastic scattering from hydrogen and radiative tail–Coincidence between electron in HRS-L and recoil p in BigBite–Cut on W= 938.5 -1700 MeV
P = 300 - 800 MeV/c, HRS-L 45 - 80 degrees.• Vertex reconstruction accuracy - multi foil C target
–BigBite at 48 Deg• Beam energy calibration-
– Elastic scattering from Ta, C, H• Efficiency of detection system
– Measure elastic cross section H
HRS-L at 45 Deg, BigBite at 48 Deg•Luminosity monitor HRS-R
Run Plan Production running
• BigBite Calibration Measurements HRS-L at 40-80 Deg BigBite at 42 Deg– Production Running HRS-L at 12.5 Deg., BigBite at 42 Deg– Production Running HRS-L at 14.7 Deg., BigBite at 42 Deg– Production Running HRS-L at 16.6 Deg., BigBite at 42 Deg
• BigBite Calibration Measurements HRS-L at 40-80 Deg., BigBite at 48 Deg– Production Running HRS-L at 12.5 Deg., BigBite at 48 Deg– Production Running HRS-L at 14.7 Deg., BigBite at 48 Deg– Production Running HRS-L at 16.6 Deg., BigBite at 48 Deg
• BigBite Calibration Measurements HRS-L at 40-80 Deg., BigBite at 54 Deg– Production Running HRS-L at 12.5 Deg., BigBite at 54 Deg– Production Running HRS-L at 14.7 Deg., BigBite at 54 Deg– Production Running HRS-L at 16.6 Deg., BigBite at 54 Deg
• HRS-R fixed at 90 Degrees
Milestones
• March – Design/Draft windows in Clamshell Flanges (2)– Design/Draft Coffee Can Collimator– Design/Draft shape of polyurethane helium containment balloon– Design ways of coupling balloon to chamber– Order sample polyurethane balloon material
• April– Design Helium gas handling system for balloon– Design 4 cm pancake cell - D. Meekins.– Order prototype polyurethane balloon( 0.005” thick) and prototype 10 m mylar pillow shape balloon. Order two extra balloons for protecting PMTs from helium leaks– Finalize mechanical hardware design (Lindgren) and have CAD drawings made
for integration into the system(Jlab).– Middle Wire chamber shipped to UVa for upgrade to 6 wire planes
• May– Test prototype balloons for helium leak rate and radiation damage
Milestones
• June – Upgraded wire chamber shipped to JLab for testing
• July – Install upgraded wire chamber into frame.– Start and complete machining clamshell flanges, collimator, and
window components
• August– Assemble flanges, collimator, window, gas handling system, and
balloon for further testing.
• September – Check out all new hardware, electronics, and hadron package. Make
sure it all works. (Need milestones for hadron package)
• November - December – Review, Check out Run Plan, Check BigBite scintillators and wire
planes with Cosmic rays, check discriminator levels and high voltages. Check out trigger electronics with cosmic rays.
• Jan 2008– Install pi0 experiment - one month
• Feb 2008 – Run pi0 (32 days)
People Power
• Overview and Run Plan R. Lindgren, B.E. Norum (UVa)
• GEANT Calculations V. Nelyubin (UVa)
• Target Design and Construction D. Meekins (JLab)
• Design of new Clamshell, Coffee Can
Collimator, Helium Bag system R. Lindgren (UVa)
• CAD Drawings JLab
• Middle Wire-Chamber Upgrade M. Shabestrai (UVa Grad. Student)
N. Liyanaga (UVa)
• Hadron Package for BigBite X. Zhan (MIT) Grad. Student
• Hadron Electronics for BigBite B. Moffit (MIT) Research Associate
• Shifts The BigBite Family
Safety Documentation
• This research will be conducted in a manner that ensures that environmental, health, and safety (EH&S) and radiation safety (ALARA) concerns receive the highest consideration yet maintain the programmatic goals of the laboratory in producing the highest quality results efficiently.– Conduct of Operations (COO)
– Experiment Safety Assessment Document (ESAD)
– Radiation Safety Assessment Document.