The VEPP-4M Collider Operation in the Experiment of Precise Tau-lepton Mass Measurement

The VEPP-4M Collider OperationThe VEPP-4M Collider Operationin the Experiment of in the Experiment of

Precise Tau-lepton Mass MeasurementPrecise Tau-lepton Mass Measurement

V. Smaluk, for the VEPP-4 teamV. Smaluk, for the VEPP-4 team

Budker Institute of Nuclear Physics, NovosibirskBudker Institute of Nuclear Physics, Novosibirsk

The VEPP-4M lab http://v4.inp.nsk.suThe VEPP-4M lab http://v4.inp.nsk.su

6-th International Workshop on Accelerator Operations6-th International Workshop on Accelerator Operations

Trieste, 24-28 September 2007Trieste, 24-28 September 2007

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ContentsContents

• The VEPP-4 accelerating-storage complex • High-energy physics experiments• Operation time distribution• Failure analysis• Working cycle automation• Performance improvement

The VEPP-4M Collider Operation in the Experiment of The VEPP-4M Collider Operation in the Experiment of Precise Tau-lepton Mass MeasurementPrecise Tau-lepton Mass Measurement

6-th International Workshop on Accelerator Operations, Trieste, 24-28 September 20076-th International Workshop on Accelerator Operations, Trieste, 24-28 September 2007

http://v4.inp.nsk.suBINPNovosibirsk

The VEPP-4 accelerating-storage complexThe VEPP-4 accelerating-storage complex


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The VEPP-4 accelerating-storage complexThe VEPP-4 accelerating-storage complex


http://v4.inp.nsk.su


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High-energy physics:High-energy physics: -lepton mass measurement-lepton mass measurement

Precise measurement of the -lepton mass at the producing threshold is the principal high-energy physics experiment at the VEPP-4 accelerating-storage complex.

Exact value of the -lepton mass is required to verify the lepton universality principle which is one of the postulates of the Standard Model, the most complete theory describing fundamental properties of matter.

At present, measurement accuracy reached in this experiment is the best in the world.




http://kedr.inp.nsk.su

MeV 80.1776 2006 KEDR

MeV 77.1776 2006 BELLE

MeV 96.1776 1996 BES

MeV 90.1776 2006PDG

25.023.0

35.035.0

31.027.0

29.026.0

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High-energy physics: High-energy physics: (2s) and (2s) and (3770)(3770)

Precise measurements of the family meson masses provide the energy scale in the range around 3 GeV which is a basis for accurate determination of masses for all charmed particles.

MeV 0.60.93773.5

MeV 0.0150.0123686.117

(3770)

(2S)

M

M 3 times improved

2 times improved

There are only 5 masses (e, p, n, , ) measured with higher

accuracy




http://kedr.inp.nsk.su

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Beam energy measurementBeam energy measurementResonant depolarization – high-precision periodic calibration




Compton back-scattering – routine energy monitoring during HEP experiment runs

165.440[MeV]

0sE

00 1

qq

s

610EE

Measurement accuracy

5105 EE

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Synchrotron radiation experimentsSynchrotron radiation experiments




http://ssrc.inp.nsk.su

0a – LIGA-technology and X-ray lithography0b – “Explosion" 2 – Precision diffractometry and anomalous scattering3 – X-ray fluorescence analysis4 – High-pressure diffractometry5a – X-ray microscopy and micro-tomography5b – Time-resolution diffractometry5c – Small-angle X-ray scattering6 – Time-resolution luminescence7 – SR beam stabilization8 – EXAFS spectroscopy10 – Metrology and EXAFS spectroscopy in soft X-ray band

VEPP-3 SR channels and stations

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Distribution of the operation timeDistribution of the operation time




2004 - 2006

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Experiment timeExperiment time




2000 - 2006

0

1000

2000

3000

4000

5000

6000

hours

SR HEP

HEP 48 372 906 0 2226 2718 3540

SR 2181 1881 1992 2626 1428 2220 2232

2000 2001 2002 2003 2004 2005 2006

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OperationOperation




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Shift supervisor

Technician on duty

Services:power service,

vacuum,cooling water,conditioning,

transport,etc.

SR userscoordinator

KEDR detector operator

On-call personnel:injector,

magnet power supplies, RF system,

injection/extraction,beam diagnostics,

control system,electronics,software.

SRusers

KEDRon-call

personnel

Shift supervisors:12 physicists, 4 engineers,2 post-graduate students

Machine control and monitoringMachine control and monitoring




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Control room workstations

Injectorcontrol

VEPP-3magnet system

VEPP-3RF system

VEPP-3beam monitoring

VEPP-4Mmagnet & RF

systems

VEPP-4Mbeam

monitoring

Vacuum,temperature,

radiation

KEDRmonitoring

Injectormonitoring

Transport linecontrol

Transport linemonitoring

Ethernet

On-line status in the wwwOn-line status in the www




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DatabaseDatabase

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• PostgreSQL database

• more than 1500 parameters of beams and accelerators

• 1-second samples are available during last 24 hours

• 30-second samples are stored for 1 year

• older data are available from an archive storage

• a set of typical data request scripts is developed

• GUI

Working cycle in a HEP experimentWorking cycle in a HEP experiment




• accumulation of positrons in the VEPP-3 (15-20 minutes), • acceleration up to the extraction energy (5 minutes), • bunch-by-bunch extraction and injection into the VEPP-4M, • magnetic cycle and polarity change of the VEPP-3 and Injector (5 minutes), • electron accumulation (1-2 minutes), acceleration and injection into the VEPP-4M.

Total time required to refill beams in the VEPP-4M is 30-40 minutes.

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Working cycle automationWorking cycle automation




luminositybeam currentsbeam energiesbetatron tunes

beam sizesbeam orbits magnet fields

timingtemperatures

etc.

“Autopilot”

Luminositycontrol

Betatron tunes

Betatron coupling

Beam matching at IP

VEPP-4M beaminjection control

e+/e- accumulationin the VEPP-3

VEPP-4M injection

Beam separation at IP

Acceleration

Injector control

VEPP-3 magnet cycle

Polarity change

Injector

VEPP-3

Transport lines

VEPP-4M

KEDR

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86.6

77.7

104.097.6

94.0

102.0

83.1

92.3

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114.7

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95.7

92.2

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84.7

97.4

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Average luminosity in HEP shifts




Results of working cycle automationResults of working cycle automation

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Working time lossWorking time loss




incoming power failure,

cooling water overheat or leakage,

vacuum deterioration

including operator trainingon-the-run

Magnet systems,

RF systems,

beam diagnostic instruments,

beam energy measurement systems,

etc.

both system and application

control computers, CAMAC electronics, low-power circuitry of the magnet power supplies and RF systems

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Failure recoveringFailure recovering




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Failure indication:no luminosity,

beam loss,alarm,

etc

Repair by the shift staff(replace defective devices)

Fault analysis

Complex

Search fault location

Call theexpert

Easy

Return tooperation

Repair by the expert Switch off the machine

Phone to anexpert

YesNo

No

Yes

Performance improvement:Performance improvement:Temperature monitoring systemTemperature monitoring system




One of peculiarities of the HEP experiments realized at the VEPP-4M is the high-precision beam energy evaluation.

To estimate the beam energy between absolute calibrations by the resonance depolarization method, an empirical formula is used.

This formula gives 20 keV accuracy of energy interpolation using the dipole magnetic field and temperature of the magnets, tunnel walls, cooling water, etc.

On-line monitoring of the magnetic field with

10-6 accuracy is realized by the nuclear magnetic resonance method.

For the precise temperature monitoring, a new system has been developed.

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Hardware:

High-Precision Digital Thermometers DS1631 with the resolution of 0.0625oC and absolute accuracy of 0.5oC in the 0–70oC temperature range.

32-channel controller developed in BINP: automatic scanning of the temperature sensors every second and data writing into the internal memory;

relay interlock function to prevent overheat.

Software:

Control program reads data from the all the controllers and writes it to a PostgreSQL database.

GUI is also developed.




The controller.

1 – temperature sensor board;2 – sensor inside the protection case.

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Performance improvement:Performance improvement:Temperature monitoring systemTemperature monitoring system

Performance improvement:Performance improvement:Thermostabilization of the magnetsThermostabilization of the magnets

Measured diurnal variations of the VEPP-4M beam energy.

Main factor - temperature drift of the VEPP-4M magnets.

Perturbing factors:

ambient temperature, atmospheric humidity,conditions in a cooling tower, etc.

Double-loop water cooling system

High-precision thermal sensors

Computer-controlled valve




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Thermostabilization OFF Thermostabilization ON




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Performance improvement:Performance improvement:Thermostabilization of the magnetsThermostabilization of the magnets

Unstable phase oscillation occurs due to parasitic high-order modes of the VEPP-4M RF cavities. This instability is one of the main efficiency decreasing factors, because it reduces luminosity drastically. High-amplitude phase oscillation leads to particle loss and can be dangerous for the KEDR detector.

RF cavity temperature variation results in the cavity deformation and then leads to a shift of working conditions away from the stability regions.




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Performance improvement:Performance improvement:Thermostabilization of the RF cavitiesThermostabilization of the RF cavities

19

19,5

20

20,5

21

21,5

22

0 10000 20000 30000 40000 50000 60000

Time (s)

T,

deg

ree

Thermostabilization OFF, t=2oC

24,9

24,92

24,94

24,96

24,98

25

25,02

25,04

25,06

25,08

25,1

0 10000 20000 30000 40000 50000 60000

Time (s)

T,

deg

ree

Thermostabilization ON, t=0.5oC

Temperature is measured by thermo-sensors with a sensitivity of 10 mV/oC.

For each RF cavity, 5 kW flowing water heater is switched on/off by controllable electronic switches.

Temperature analysis and power control is provided by a microcontroller.




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Performance improvement:Performance improvement:Thermostabilization of the RF cavitiesThermostabilization of the RF cavities

Luminosity integral 2004 – 2006Luminosity integral 2004 – 2006




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The VEPP-4 teamThe VEPP-4 teamPhysicist and

post-graduate students EngineersLaboratorytechnicians

A.AleshaevA.BogomyagkovS.KarnaevV.KiselevE.KremyanskayaE.LevichevO.MeshkovS.MishnevI.MorozovN.MuchnoiS.NikitinI.OkunevV.PetrovP.PiminovYu.PupkovE.SimonovS.SinyatkinV.SmalukG.TumaikinD.ShatilovA.Zhuravlev

O.AnchugovI.BannikovM.BokovM.BrovinD.BurenkovS.VasichevYu.GlukhovchenkoO.GordeevV.ErokhovA.ZhmakaV.NeufeldO.PlotnikovaA.PolyanskiyV.SandyrevV.SvischevI.UtjupinM.FominD.Shvedov

A.ApanasenkoG.BelyakovV.BykovA.KolesnikovG.KurganovP.KoshkinI.LubyaginA.MaslovI.MishinA.PetrovA.PoroshinI.RomanovS.RudakovP.SvischevA.SoshilovL.StebailoN.TurV.TuraevA.ChabanovV.Shvaibovich

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Thank you for your attentionThank you for your attention

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Documents

The VEPP-4M Collider Operation in the Experiment of Precise Tau-lepton Mass Measurement