proposal for a programme of neutrino factory r&d introduction bath, rmcs shrivenham, daresbury,...
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Proposal for a programme of Neutrino Factory R&D
Introduction
Bath, RMCS Shrivenham, Daresbury, Glasgow, Liverpool, Imperial College, Oxford, RAL, QMUL, Sheffield
High Power RF Faraday Partnership
K. Long, 11 April 2023
Neutrino Factory: physics case Neutrino oscillations – established exptly
Implications for particle physics: Neutrino mass > 0 CP violation in the lepton sector?
Impact on astrophysics and cosmology: Origin of matter (leptogenesis) Dark matter
Require dedicated exptl programme to: Search for leptonic-CP violation Precisely measure parameters
Neutrino Factory: concept
NF: UK contributions to date- Proton driver:Schemes for:
RAL: NF and ISIS upgrades based on RCS
CERN: RCS in ISR tunnel
Contribution to SPL
Fermilab: Contribution to design of 8 GeV booster
J-PARC: Contribution to 3 GeV proton ring
NF: UK contributions to date5 MW proton driver developed from ISIS synchrotron
NF: UK contributions to date- Proton driver:
CERN:
30 GeV rapid cycling synchrotron in the ISR tunnel
NF: UK contributions to date- Targetry: Target system:
Power dissipation and thermal shock:
Rotating solid band (see R. Bennett)
Particle production and capture
HARP: Target assembly
Software
Leadership in analysis
Data taking complete
NF: UK contributions to date- Muon front end: Ionisation cooling:
Principle::
MuScat:Measure MCSdistributions
Practice:
MICE
Simulation: Ring coolers
Alternatives
Data taking complete
NF: UK contributions to date- international Muon Ionisation Cooling Expt:
142 authors, 37 institutes, 3 continents!
NF: UK contributions to date- MICE
The vision: neutrino physics
Prepare for era of precision neutrino physics
Worldwide consensus:
Neutrino Factory physics programme is:
Of fundamental importance
Complementary to that of LHC and LC
Neutrino Factory is the tool of choice
Therefore likely that it will be built. So:
The vision: UKNF proposal 2003 Programme of accelerator R&D that will:
Give the UK ownership of the key technologies: Proton driver front end Targetry Ionisation cooling
Conceptual design of complete facility: Embed results of hardware R&D Optimise entire complex
This will position UK to : Position UK to play lead role Possibly also to bid to host the facility
UK Neutrino Factory R&D activity
UKNF
MICE-UKWP1Conceptual
design
WP2Proton driver
front end
WP3Target studies
WP4Neutrino Factory design studies
D. FindlayR. Bennett
R. Edgecock
UK Neutrino Factory R&D activity
0
2000
4000
6000
8000
10000
12000
14000
1 2 3 4 5 6
Years (from 2004)
An
nu
al C
ost
(£k
)
WP3-TS
WP4
WP3 (ex TS)
WP2
WP1
Present request
04/05 05/06 06/07 07/08 09/09 09/100
2000
4000
6000
8000
10000
12000
14000
1 2 3 4 5 6
Years (from 2004)
An
nu
al C
ost
(£k
)
WP3-TS
WP4
WP3 (ex TS)
WP2
WP1
Present request
04/05 05/06 06/07 07/08 09/09 09/10
Front end test stand — WP2
Work package manager:David FindlayAccelerator DivisionISIS DepartmentRutherford Appleton Laboratory
Michael Clarke-GaytherAlan LetchfordJohn Thomason
Why interest in front end?
Front end of machine is where
currents and duty cycles are set for whole machine
beam quality is set for whole machine
UKNF: 4 MW — Front end must be good!
Multi-megawatt proton accelerators are new
Neutrino factories
Neutron sources, transmutation,tritium, energy, etc.
1 W/m loss max., ~10—7 loss per metre
Strong overlap
Neutrino factory proton driver:
Ion source (65 mA)
LEBT (low energy beam transport)
RFQ (75 keV 2.5 MeV, 280 MHz)
Chopper (typically ~30% chopped out)
DTL (2.5 MeV 180 MeV, 280 MHz)
Achromat
Synchrotrons
Front end must be good, so need a front end test stand to make sure!
Front end
Ion source: H—, 65 mA, 400 µs
2 × 2 × world’s leading H— source — ISIS
Existing negative ion source development programme at RAL for HPPAs in general
ASTeC
EU (network HPRI-CT-2001-50021)
This ion source programme a benefit to UKNF front end test stand programme
Ion Source Development Rig at RAL
LEBT and RFQ
Low energy beam transport
Matches 65 mA from ion source to RFQ
RFQ
4-rod, 75 keV 2.5 MeV, 280 MHz
These less of a problem
Can base on experience of LEBT and RFQ for ISIS and outline designs for ESS
More a matter of implementation than R&D
But ~1–2 MW RF driver required for RFQ
UKNF RFQ will be ×3 longer and in square section vessel
Beam loss
Why chopper?
Ion source Linac Ring
Bunching
Also to minimise RF transients and control beam intensity
>10 × ISIS
No beam loss
Ion source Linac Ring
Bunching
With chopper — gaps in beam
Good
Bad
Chopper performance required
DC accelerator
RF accelerator
ns – µs spacing
UKNF: 280 MHz, bunch spacing 3.57 ns
On
Off
Switch between bunches
Partially chopped bunches a problem! Tune shifts!
Choppers across the world:
SNS 402 MHz, slow — only chopper built
CERN 352 MHz, SPL — work proceeding
RAL 280 MHz, fast, rugged, “UK”
SNS, 2½ ns per bunch
LEBT MEBT
RAL aspiration:switch in 2 ns and dissipate ~3–4 kW when “off”
2-stage processSlow transmission line
Lumped line — thermally hardened
0
1
0
12 ns 8
ns
RAL beam chopper— outline scheme
Need to build andtest with bunched beam
Beam
~1 m
Buncher cavity
Fast switch
Slow switch
Buncher cavity
Ion source (R&D already
under way)
LEBT
RFQ (bunches beam)
Chopper
Diagnostics
Experience of building test stands at RAL — ISIS RFQ test stand
Build test stand
Front end test stand at RAL — 3 and 6 year costs
SY £k (hardware incl. VAT + contingency)
Overall design + infrastr. 8 8 398 398
Ion source 6 7 324 347
LEBT 2 5 139 231
RFQ 1 14 46 1388
Chopper 14 48 623 1990
1530 4355 hardware
65 185 travel
30 82 1631 4495 staff
3226 9035 total
Front end test stand at RAL — time scales
Outline design Expect to build in R8 at RAL
Specifications Including monitoring/control specifications
Install infrastructure Electricity, air, water, (lead) shielding, initial monitoring/controls
Procure & install mechanical support structures HV platforms, LEBT + RFQ + chopper supports, etc.
Develop, procure & install ion source Source, vac., HV sys., arc & extract drivers, monitoring/control
Design, procure & install LEBT (incl. diagnostics) 3-solenoid LEBT incl. emittance scanners
Design, procure & install RF driver for RFQ 1½ MW likely to be required
Design, procure & install RFQ 2–3 MeV, 4-rod, based on existing ESS design
Chopper: design & test off-line Slow & fast deflection systems without beam
Chopper: design complete system Incl. quadrupoles & RF buncher cavities
Design, procure & install beam diagnostics (at output of chopper) Long. & trans. emittances
Chopper: procure & install
Run complete test facility
2009–10 2010–11 2011–122005–06 2006–07 2007–08 2008–092004–05
Year 5 Year 6 Year 7 Year 8Year 1 Year 2 Year 3 Year 4
Front end test stand at RAL
Six-year programme to build
Costed on basis of test stand already built and working
~£4½M equipment
~80 staff-years
RAL + university staff
Physics and engineering of real accelerator facility
Proposal for a programme of Neutrino Factory research and development
WP-3 The Target
The Neutrino Factory Target
Work Package Manager - J R J Bennett
CCLRC, RAL
Schematic diagram of the target and collector area
proton beam 4 MWtarget 1 MW
beam dump
pion collector solenoids
to the muon front-end
3 MW
s/s
thick shield walls
ParametersProton Beam pulsed 10-50 Hz pulse length 1-2 s energy 2-30 GeV average power ~4 MW Target (not a stopping target)
mean power dissipation 1 MW energy dissipated/pulse 20 kJ (50 Hz) energy density 0.3 kJ/cm3 (50 Hz)
2 cm
20 cm
beam
Target Developments – so far
1. Mercury Jets (USA and CERN)
2. Contained Flowing Mercury
3. Granulated Targets (CERN)
4. Solid targets (USA and RAL)
5. Solid Rotating Ring (USA and RAL)
• The mercury jets have had most development
• All schemes have advantages and disadvantages
The RAL scheme
Large rotating toroid cooled by
Thermal Radiation
This is very effective at high temperatures due to the T4 relationship (Stefans law).
40
41 TTAW
Schematic diagram of the radiation cooled rotating toroidal target
rotating toroid
proton beam
solenoid magnet
toroid at 2300 K radiates heat to water-cooled surroundings
toroid magnetically levitated and driven by linear motors
POWER DISSIPATION
0.01 0.1 1 10 100 1 103
0.01
0.1
1
10
100
1 103
power
MW10 m
10 m
v = 100 m/s
1 m
1 m
100 m
100 m
0.1 m
200 m
20 m10 m
2 m
0.1 m
1 m
2000 m
1000 m
radius/velocity
v = 20 m/s
v = 10 m/s
v = 1 m/s
v = 0.1 m/s
1000 m
10 m
100 m
10000 m5m radius
10 m/s velocity
Thermal Shock
Simple explanation of shock waves
inertia prevents the target from
expanding until:
the target expands by Δd
(axially)
target
the temperature rises by ΔT
Short pulse of protons
short pulse of protons
Time
t = 0
2d
t > 0
v is the velocity of sound in the target material.
Δd
v
dt
compression
tensio
nvelocity V
Shock, Pulse Length and Target Size
If a target is heated uniformly and slowly – there is no shock!
Or,
when the pulse length t is long compared to the time taken for the wave to travel across the target – no shock effect!
So,
if we make the target small compared to the pulse length there is no shock problem.
For the case of the neutrino factory target:
Assume t = 2 s, V = 3.3x105 cm s-1 , then d = 0.7 cm
Energy density is the key parameter
Table comparing some high power density pulsed targets
Facility Particle Target material
Energy density per pulse
J cm-3
Life,
no. of pulses
NuFact p Ta 318 109
(7x106 for the toroid)
ISOLDE
(CERN)
p Ta 279 2x106
Pbar (FNAL)
p Ni 7112 5x106
Damage
NuMI p C 600 Shock not a problem
SLC (SLAC)
e W26Re 591 6x105
RAL/TWI e Ta
thin foil
500 106
Proposed R&D1.Calculate the energy deposition, radio-activity for
the target, solenoid magnet and beam dump. Calculate the pion production (using results from HARP experiment)
and calculate trajectories through the solenoid magnet.
2. Model the shock a) Measure properties of tantalum at 2300 K b) Model using hydrocodes developed for explosive applications at LANL, LLNL, AWE
etc. c) Model using dynamic codes developed by ANSYS
Proposed R&D, continued
3. Radiation cooled rotating toroida) Calculate levitation drive and stabilisation systemb) Build a model of the levitation system
4. Individual bars a) Calculate mechanics of the system b) Model system
5. Continue electron beam tests on thin foils, improving the vacuum
6. In-beam test at ISOLDE - 106 pulses
7. In-beam tests at ISIS – 109 pulses
8. Design target station
solenoid
collection and cooling reservoir
proton beam
Levitated target bars are projected through the solenoid and guided to and from the holding reservoir where they are allowed to cool.
Equipment and Staff Costs over the first 3 years (excluding VAT)
Item Staff Years Cost, k£
1. Management 1 30
2. Target and Target Station Design 1 10
3. Nuclear Studies 8.9 30
4. Shock Studies 4.6
Measurements 280
Modeling 30
5. Electron Beam Tests 1
Improvements (mainly vacuum) 100
Tests 10
6. Tests at ISOLDE 1
Target 30
7. Levitation Studies 6
Theoretical studies 10
Model tests 100
VAT 110
Travel 45
Total 23.5 (£961k) 785
Year
ITEM 1 2 3 4 5 6
1. Management
2. Target Station Design
3. Nuclear Studies
4. Shock Studies
5. Electron Beam Tests
6. Tests at ISOLDE
7. Levitation Studies Individual bar studies
8. Build target station at ISIS Life Test
Decision on solid target
Time scale
Proton beam
Mercury jet Solenoid
Effective target length ~20 cm
Schematic diagram of the mercury jet target
To mercury pump & heat exchanger
Protons
Tube containing flowing mercury
20 T solenoid magnet
Schematic diagram of the contained flowing mercury target
Solid bar targetNeed to dissipate the heat:
a) water cooling difficult – “dilutes” target
b) radiation cooling not possible
c) need moving target – multiple targets
drive shaft
protons
spoke
solenoid coils
vacuum box
target
Rotating wheel target
1MW Target Dissipation (4 MW proton beam)
tantalum or carbon radiation cooled temperature rise 100 K speed 5.5 m/s (50 Hz) diameter 11 m
Plan View of Rotating Band Target (Bruce King et al)
shielding
rollersAccess
port
rollers
rollers
protonsto dump
cooling
coolingcooling
solenoid channel
1 m water pipes
x
z
Table comparing some high power pulsed proton targetsFacility Particle Rep. Power Energy Energy Life Number
Rate /pulse density of pulses/pulse
f P Q height width length volume thick material q N
Hz W J cm cm cm cm3 cm J cm-3 days
NuFact protons 50 1E+06 20000 2 2 20 63 20 Ta 318 279 1.E+09Number of pulses on any one section of the toroid 7.E+06
ISOLDE protons 1 3675 0.6 1.4 20 13 0.05 to Ta 279 21 2.E+060.0002
ISIS protons 50 180000 3600 7 7 30 1155 0.7 Ta 3 450 2.E+09
Pbar protons 0.3 1797 0.19 0.19 7 0.25 ~6 Ni 7112 186 5.E+06 Run I 3E12 ppp (Cu, SS, Inconel) Damage
Run II 5.E+12 Damage in one or a few pulses 13335
Future 1.E+13 0.15 0.15 30000
NuMI protons 0.53 0.1 0.1 95 2 C 600
120 GeV Radiation Damage - No visible damage at 2.3E20 p/cm2
4E13 ppp Shock - no problem up to 0.4 MW (4E13 at 1 Hz)8.6 s Sublimation -OK
Reactor tests show disintegration of graphite at 2E22 n/cm2
NuMI will receive a max of 5E21 p/cm2/year
Beam and Target size
Facility Particle Rep. Power Energy Energy Life Number Rate /pulse density of pulses
/pulsef P Q height width length volume thick material q N
Hz W J cm cm cm cm3 cm J cm-3 days
NuFact protons 50 1E+06 20000 2 2 20 63 20 Ta 318 279 1.E+09Number of pulses on any one section of the toroid 7.E+06
SLC e 120 5.E+03 42 0.08 0.08 2 W/Re 591 1500 6.E+05SLAC 33 GeV Rotating disc, 6.35 cm diameter, 2cm thick 26% Re
Target designed to withstand shock
Radiation damage leading to loss of strength and failure when subjected to shock
FXR e Ta 160 100LLNL 17 MeV Ta 267 10
No damage
RAL/TWI e 100 4.E+04 0.2 25 m Ta 500 up to 1E+06150 keV Thin foil 0.4 cm wide Range ~10 m
Failures probably due to oxidation in poor vacuum
Beam and Target size
Table comparing some high power pulsed electron targets