BNL Neutrino Long Baseline Neutrino Initiative
N. Simos, BNL NWG

Homestake

Baseline = 2540 Km

WHERE WE ARE– Making the physics case for the Very Long Baseline NeutrinoBeam– Conceptualizing AGS upgrade schemes that will lead to highpower (1+ MW)– Developing target/horn ideas– Embarking on an material R&D

BNL Long Baseline Neutrino Beam - Physics

The dominant term governing theoscillations is sin2(∆m322 L / 4E)
Longer Length allows oscillations to beseen at higher Energy
Cross sections are larger and energy
resolutions are better at higher Energy
A broad band beam allows coverage ofmultiple oscillation periods and observationof a distinct oscillation signature
The multiple node structure alows ∆m322 tobe precisely measured by a wavelength
rather than an amplitude (reducingsystematic errors)

BNL Super-Beam – Baseline Parameters

BNL Super-Beam – Baseline Parameters

BNL Target/Horn Working Concept
TARGET CONCEPTUAL DESIGN - CHALLENGES• Carbon-Carbon composite target (80cmlong, 6mm radius)• Selected over graphite for superior strengthand low thermal expansion• Experimental verification of graphite andcarbon-carbon response• Sublimation issues are potentially avoided• Forced He gas in annular space cools

target operating at ~ 800C
• ∆T per 1014 proton pulse ~ 170o C

Carbon-Carbon Composite Target
Temp.
23 o C
200 o C
400o C
600o C
800o C
1000o C
1200o C
1600o C
2000o C
2300o C% elongation
0%-0.023%-0.028%-0.020%0%0.040%
0.084%
0.190%
0.310%
0.405%

IS THERE AN OPTIMAL BEAM SIZE/TARGET SIZE RELATION ?

Two Beam sizes are considered – 1mm &2mm beam spots (6mm & 12mm diam.
targets respectively)
Total energy deposited on target is 5.1 &7.3 kJ respectively
Corresponding peak DTs on target are 960
C and 260 C
Yield of secondaries is being optimized.
That may lead to a beam spot/target
diameter somewhere in between
Option of Gaussian beam to flat beam isalso assessedBNL Target/Horn Working Concept
HORN CHALLENGES• Current pulse structure - Joule heating• Gamma ray heating - long term irradiation effects• Material degradation due to forced water coolingcombined with thermal fatigue• Maintaining operating temperature at safe levels•Baseline material is Aluminum (6061 T6 or 3000 series)• New alloys are considered (e.g. AlBeMet)• Task is keeping resistivity low while maintaining strength aswell as resistance to fatigue, corrosion• Heat transfer through water spray (baseline)• Horn inner conductor diameter = 14mm
• Conductor thickness narrowest section = 2.5mm• Smallest horn thickness = 1mm

CHALLENGES FOR THE INTEGRATED TARGE/HORN SYSTEMAS WE GET TO 1+ MW SYSTEM
Heat generation and removal from the target/horn system
Target thermo-mechanical response from energetic, highintensity protons
Irradiation and corrosion effects on materials
Horn/target integration issues
Horn mechanical response and long term integrity (irradiation,corrosion and thermal fatigue)
Beam windows integrated in the system to (a) separate thevacuum space in the transfer line from the final beam line to thetarget and (b) to maintain the coolant around the target in aclose-system loop

Horn temperature transients
Temperature distribution for
HORN/Target in contact

OPTIMIZATION EFFORT TO MEET THE CHALLENGE OF
1+ MW SYSTEM
Alternative new materials (e.g. AlBeMet, Toyota “Gum Metal”, etc) arebeing considered and will be experimentally evaluatedNano-structured surface film embedment is being considered as option
to protect the horn base-material – Examine other techniques for surface
treatment (e.g. culsterizing ???)Heat transfer enhancement is being evaluated through the use of nanoparticles in the cooling medium

Relevant Lessons from BNL E951 ExperimentSet out to assess:••

Solid target survival chances (graphite, carbon-carbon, inconel,superInvar, etc.)
Beam window survival (critical due to Hg)

And while at it ……
• Push the AGS intensity to 16 TP and beam spot to 0.5 mm RMS sigma• Experiment with and identify best candidate materials throughmeasured responses• Validate prediction models against measurements to gain confidence inpredicting material response and/or failure at extreme conditions• Use experimental results to benchmark energy depositions predicted by
the various Monte Carlo codes

E951Target Station Set-Up
Graphite & Carbon-Carbon Targets

ATJ Graphite Strain Data
Verification of fundamental modes of target response

Recorded strains in the middle of the graphite rod (left)
shows a bending frequency between 380-390 Hz
The prediction of the detailed model that implements thesupporting/holding fixtures of the target as close to thereal setting as possible, predicts a bending frequency of395 Hz
Also from the record, the axial “ringing” of the target hasa period of 260 to 265 microseconds. The fundamental
axial period T=2L/c (where L is target rod length and c isspeed of sound) is approximately 261 microseconds
The radial “ringing” on the other hand, which fromtheory is calculated at 150 KHz (or 6.625 microsecondperiod), is visible only in the strain record filtered by the500 KHz acquisition

ATJ Graphite Strain DataATJ Graphite Strain Comparison
BASIS FOR HADRON CALCULATIONS BENCHMARKINGATJ Graphite Strain Comparison
BASIS FOR HADRON CALCULATIONS BENCHMARKINGATJ Graphite vs. Carbon-Carbon Composite
BNL E951 Target Experiment
24 GeV 3.0 e12 proton pulse on Carbon-Carbon and ATJ graphite targets
Recorded strain induced by proton pulse
10C-C composite
ATJ Graphite86Microstrain420-2-4-6-800.0002

0.00040.0006Time (sec)

0.00080.001

Recent BNL Irradiation Studies on Super Invar & Inconel-718

Irradiation Studies at BNLSuper-Invar Irradiation Study

WHY STUDY super Invar ?
•High-Z with low CTE (0-150 oC)•How is CTE affected by radiation?
•What happens to other important properties?

Solid Target Option: Super-Invar Irradiation StudySummary

Super-Invar Irradiation Study – Temperature Effects

Effect of Heat Treatment in non-Irradiated Invar Samples
2500

non treated Invar
Temp (300 C)
Temp (500 C)
2000

Load (N)

1500

1000

500000.05

0.10.15
Extension (mm)0.20.25

Super-Invar Irradiation Study – CTE assessment
Super-InvarInconel 718

WHAT’S NEXT ?
• Assessment of long-term survival of baseline target & horn
materials (Aluminum & Carbon-Carbon)• Repeat irradiation/mechanical property changes experimentfor baseline materials• Experimentally verify the compatibility of cooling agentswith baseline materials (corrosion, sublimation)• Explore innovative schemes to enhance heat transfer andmaterial protection (nano-structured films, nano-fluids, etc.)• Explore new materials such as AlBeMet, Toyota’s “GumMetal” Titanium Alloy, Vascomax, Titanium (6Al-6Va)• Explore the possibility of using He for heat removal for theintegrated target/horn system

What are some of these new materials we plan to examine ?