neutrino beam design considerations stephen kahn brookhaven national laboratory
DESCRIPTION
Neutrino Beam Design Considerations Stephen Kahn Brookhaven National Laboratory Presented to the BNL March 3, 2004. Outline of talk. Description and status of the proposed Deep Underground Science and Engineering Laboratory (DUSEL). - PowerPoint PPT PresentationTRANSCRIPT
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 1
Neutrino Beam Design Considerations
Stephen Kahn Brookhaven National Laboratory
Presented to the
BNLMarch 3, 2004
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 2
Outline of talk
Description and status of the proposed Deep Underground
Science and Engineering Laboratory (DUSEL).
Physics of a Very Long Baseline Neutrino Oscillation
Experiment.
Status of VLBL experiment at Brookhaven National
Laboratory.
Opportunities for Long Term Collaboration.
http://int.phys.washington.edu/NUSEL
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 3
BNL Homestake Long Baseline Neutrino Beam
2540 km
Homestake BNL
•28 GeV protons from the AGS
•1 MW beam power from upgraded proton driver
•500 kTon Water Cherenkov Detector
•Conventional Horn Focused beam
Baseline Design:
•Alternate detector technologies are being considered.
•Alternate detector sites such as the WIPP facility in New Mexico and the molybdenum mines in Colorado would be acceptable.
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 4
The Wide Band Neutrino spectrum from the AGS
Proton energy 28 GeV 1 MW total power ~10
14 proton on target per pulse Cycle at 2.5 Hz Pulse width 2.5 s Horn focused beam with graphite
target Flux at 1 km: 5x10-5 /m2/POT 52000 CC events during 5107 sec. 17000 NC events during 5107 sec.
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 5
Anti-neutrino Wide Band Spectrum from the AGS
28 GeV proton energy with a 1 MW proton driver source.
1014 protons per pulse cycled at 2.5 Hz
Horn focused beam with opposite current setting
We would expect ~60000 non-oscillating events at Homestake for with a 2 MW power source in 5107 sec.
There is a significantly larger contamination in the
spectrum
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 6
1 Degree Off-Axis Beam Option
The neutrino beamline can be designed with an option to run an off axis beam. The horn can be designed to be
moved and oriented for a 1º off axis beam.
The decay tunnel would need a larger 4 m diameter.
The spectrum shown has a narrower energy spread than the standard wide band beam. The off-axis beam is significant
for 0.5-3.0 GeV instead of 0.5-5.0 GeV for the wide-band beam.
The e/ ratio is significantly in the range where is significant.
BNL Off-axis Beam Option
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 7
Advantages of a Very Long Baseline
DISAPPEARANCE
0
50
100
150
200
250
0 1 2 3 4 5 6 7 8 9 10
Reconstructed Energy (GeV)
BNL-HS 2540 km
sin2223 = 1.0
m2 32 = 2.5e-3 eV2
1 MW, 0.5 MT, 5e7 sec
No oscillations: 13290 evts
With oscillations: 6538 evts
Background: 1211 evts
neutrino oscillations result from
the factor sin2(m322 L / 4E)
modulating the flux for each
flavor (here disappearance)
the oscillation period is directly proportional to distance and inversely proportional to energy
with a very long baseline actual oscillations are seen in the data as a function of energy
the multiple-node structure of the very long baseline allows the
m322 to be precisely measured
by a wavelength rather than an amplitude (reducing systematic errors)
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 8
Very Long Baseline Neutrino – m322 Nodes
neutrino node pattern is key to high-resolution m2 measurements
Fermi momentum sets E>1 GeV/c to maintain energy resolution
the distance scale is set by m23
2
BNL-HS 2540 km FNAL-HS 1290 km BNL-WIPP 2880 km BNL-Henderson 2770
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 9
BNL-AGS Target Power Upgrade to 1 MW
AGS is currently the highest intensity machine. Simple plan. Run the AGS faster. 2.5 HzNeed new LINAC @ 1.2 GeV to provide protons.Cost $265M FY03 (TEC) dollars.Energy is 28 GeV. 2.5 Hz operation is 1 MW
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 10
Super Neutrino Beam Geographical Layout
BNL can provide a 1 MW capable Super Neutrino Beam the neutrino beam can aim at any site in the western U.S.; the Homestake Mine is shown here
there will be no environmental issues if the beam is produced atop the hill illustrated here and the beam dumped well above the local water table construction of the Super Neutrino Beam is essentially de-coupled from AGS and RHIC operations
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 11
3-D Neutrino Super Beam Perspective
•The beamline is inclined 11.3º with respect to ground level to reach the Homestake mine
•Shielding is removed in figure to see the beamline.
•The hill is designed such that the target station, decay tunnel and beam dump are above the water table
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 12
Elevation View of Beamline
The extracted beam from the AGS first follows the existing U-line.
It is bent upwards by 11º with a single 90º phase advance cell.
It is bent horizontally 68º with a 4 cell system having a 90º phase advance.
It is finally bent downward by 11.3º to aim at Homestake. It is focused to a 2 mm
radius on the target. The top of the hill is 49 m
above ground level.
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 13
Alignment Issues – Criteria
We need to be able to establish the expected flux at the far detector to a precision to adequately perform the physics
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 14
Radiation Safety and Shielding issues
•Our current conceptual design for this proposed neutrino facility must meet and does meet all the necessary standards for radiation protection.
•MCNPX calculations of radiation pattern near shielding
•This includes chronic exposure in adjacent areas and offsite.
•The design also prevents contamination of the ground water.
9 m of soil shielding over decay tunnel
9 m of Fe shielding for beam dump
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 15
The Near Detector Station The near detector facility will be located at
285 m from the target just after the beam stop.
This location is constrained by the steep incline of the beamline.
The near detector will not see the beam as a point source. Extracting flux information at the far
detector will require an analysis similar to that to be used at JPARC.
The detector technology used for the close detector should be similar to that used at the far detector in order to minimize systematic errors.
Parameter Value Distance from Target 285 m Depth Below Ground 21 m
Enclosure Length 15 m Enclosure Height above Floor 5 m
Enclosure Width 6 m (?)
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 16
AGS 1 MW Upgrade and SC Linac Parameters
Proton Driver Parameters
Item Value
Total beam power 1 MWProtons per bunch 0.41013
Beam energy 28 GeVInjection turns 230Average beam current 38 mARepetition rate 2.5 HzCycle time 400 msPulse length 0.72 msNumber of protons per fill 9.6 1013
Chopping rate 0.75Number of bunches per fill 24Linac average/peak current 20/30 mA
Superconducting Linac Parameters
Linac Section LE ME HE
Av Beam Pwr, kW 7.14 14.0 14.0Av Beam Curr, mA 35.7 35.7 35.7K.E. Gain, MeV 200 400 400Frequency, MHz 805 1610 1610Total Length, m 37.82 41.40 38.32Accel Grad, MeV/m 10.8 23.5 23.4norm rms , mm-mr 2.0 2.0 2.0
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 17
1 MW Target for AGS Super Neutrino Beam
1.0 MW He gas-cooled, Carbon-Carbon target for the Super Neutrino Beam
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 18
Target and Horn Design The target is made of a carbon-carbon
composite. This is a 3D weaving of carbon fibers. It is a low Z material. It exhibits low thermal expansion up to
1000 C. elongation< 0.04% in this range Thermal shock to the target is greatly
reduced. It exhibits much greater structural strength
than graphite. The target will be cooled by convection from
forced helium flow The energy deposit in the target should be
7.3 kJ per pulse. Including heat deposited in the horn from
radiation and electro-thermal heating of the horn, we would like to remove 18.25 kJ per pulse. Helium flowing at 40 m/s will keep the
temperature to T840 °C
Parameter Value
Target Material Carbon-Carbon CompositeTarget Radius 6 mm
Target Length 80 cm
Horn Inner Radius 7 mm
Horn Outer Radius 61 mm
Horn Inner Conductor Thickness
2.5 mm
Horn Length 217 cm
Target Density 1.9 g/cm3
•The target is 1.5 interaction lengths long.
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 19
The Target and Horn Enclosure
Parameter Value Material Aluminum
Horn Current 250 kA Horn 1 Inner Radius 7 mm
Horn 1 Inner Conductor Thickness 2.5 mm Horn 1 Length 217 cm
Horn 1 Inductance 779 nH Horn 1 Resistance 248
Horn 2 Inner Radius 58.4 mm Horn 2 Inner Conductor Thickness 1.6 mm
Horn 2 Length 150 cm Horn 2 Inductance 287 nH Horn 2 Resistance 30
Stripline Inductance 480 mH Stripline Resistance 30
Pulse Width 1.2 ms Repetition Rate 2.5 Hz
Distance Betw. Horn Fronts Plates 8.17 m
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 20
Power Supply Issues
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 21
Target and Horn Material R&D
The materials choices for the target and horn of a 1+ MW system are challenging. Must survive the heat generated from the beam. The target must have minimum thermal-mechanical
response to the beam. Materials must survive irradiation and corrosion
effects. We have been examining new materials that can be
used with proton sources with more than 1 MW.
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 22
BLIP Irradiation Studies
We are in the process of irradiating possible target materials in the BLIP facility at BNL. The samples will receive
exposures representative of the expected lifetime of the neutrino facility.
Target materials that will be examined (in the next few weeks) are Carbon-Carbon Composite Titanium Ti-6 Al-4V alloy Toyota Gum Metal
High strength, near-zero expansion coefficient
Vascomax AlBeMet
Aluminum-Beryllium alloy. Horn material
Nickel-plated T6062 Aluminum that is being used in the NuMI horn
Thermal expansion of Super-Invar as a function of atom displacements
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 23
Estimated Costs and Schedules of the Proposed Neutrino Facility
•These are preliminary total estimated costs (TEC) in FY03 dollars including
•EDIA (15%)
•Contingency (30%)
•BNL overhead
March 3, 2004 S. Kahn
AGS Long Baseline Neutrino Beam Page 24
Summary
Technically feasible R&D items Cost is manageable