Ring magnetic field compensation

A long time a go we have seen that when the magnets of the storage ring are cycling the beam on the linac "moves". I remember a day in the control room of Alba doing a test on the cycling procedure (no beam in the storage, the machine was mine) I hear the scientist working on the linac, just in a computer besides the one I was using, saying "We are not changing anything and the beam is moving horizontally!"


AFAIK the problem is coming from the thing that the bending magnet  of the storage ring (and the same thing with each family of sextupoles) are powered from the same power converter. There is one power converter in sector 1 for all the (32) storage ring bending magnets. Each magnet is a solenoid, but the cable to distribute the power to all of them can be saw globally like on big solenoid with one turn.


In the storage ring, there are also 9 families of sextupoles, each of them powered by converters also placed in sector 1, with the same situation than the bendings. This means that, globally, we have 10 solenoids of one turn of 268.8 meters. 


(There are also 14 families of quadrupoles, but in that case there is one power converter per sector and is not contributing to this problem.)


How to compensate this? The problem is not when the storage ring magnets are cycling, the issue is when this magnets have set different currents due to many different purposes forces to reconfigure the linac. The easy and smarter solution perhaps is to install another turn to compensate the effect.


Then when the setting of the storage changes, the current of one extra power converter changes to cancel the effect on the linac. But calculate and apply new current values it's a boring thing for a human. Often I say the repetitive and boring task are good for computers, and gives free time to humans.


One detail more, some of the magnet turns goes clockwise direction in the storage ring, and some others goes in counter-clockwise direction. That means that they already cancels some of their effects but 0 effect is not grant. That the goal of this compensation turn.

A device server class with the name "RingMagnetCompensarion" is the responsible in the control system to calculate the current to set in the power converter for the compensation turn. This device has some properties:

• [Counter]ClockWise: two lists of magnet device server names
• MagnetAttr: name of the attribute to read/subscribe on the magnets of the lists
• CompensationMagnet: name of the device server where the calculated compensation current will be written
• AttrThreadSleep: Expert property to fine adjust of the refresh on the threaded option of the magnets current refresh

How it works? When the device is started, it composes the lists of clockwise (cw) and counterclockwise (ccw) in two different magnet groups. In the constructor, each of this magnet groups will create a list of particular magnets. And are this particular magnets the ones responsible for each reading on the devices of the power converters.

This Magnet class, checks if the attribute to read in the power converter device server have events or not. In case of event, it subscribes to it, but if not, if does a polling to read if the current have changed.

When a magnet object receives from its attrManager the notification of a readback change, this is propagated to the magnetGroup parent object. Why? Because this with update the cw/ccw list of currents and update the summatory. With this summatory updated, it's time to notify the RingMagnetCompensation device to calculate the formula:

Then only rest the event propagation and to write in the compensation power converter device if it's necessary.

Issues: One detected issue that has been already fix is when the magnets are cycling. The compensation power converter range is between 50A to -50A, and during cycling procedure this can be out of this range. Then each magnet object checks if the subdevice have received a command Cycle() to cut the propagation of readback change.

Another issues is the SlewRate of all the power converters involved. This has not tested yet, but it's possible that the speed changing the current in the compensation power converter would be not faster enough to a live response against the current changes on all the magnets in the lists.

Alba Synchrotron Vacancies

Yesterday, 3 new job offers has been publish in the Alba's website with a few minutes of delay between them:

First was the Accelerator Division Head:

A few minutes later, a position for Experiments Division Head:

And finally, also with a small number of minutes delay, a position for a Director of the facility:

Differences between this offers are "minimals". I mean, for sure they have different functions, but the conditions looks to be the same.

We are still having an acting director and even if the previous experiment division head says that we didn't suffer the Spanish cuts, the reality is that we suffer salaries cuts. All the personnel of Alba (cells) have our salary cut due to a Spanish law. If anyone can think that the cuts didn't affect us, see also that many people left the company during next months after the cut.

But not every thing is bad. A few days a go, the call for experiments proposals from the user office, have finish and we have received hundreds of them. And not only from inside Spain.

First friendly users will come very soon. We are almost ready:

Hollywood industry origin against piracy

Which was the origin of Hollywood? I have read what wikipedia says in the third paragraph of the previous link:

  Various producers and filmmakers moved bases from the east coast to escape punitive licensing from the Motion Picture Patents Company.

A funny reading of that can be, the ones who nowadays are "injured" due to the piracy have started their business with tricks to avoid payments on a patent. The ones who nowadays are moving the flag about the intellectual property menace against piracy, they was the ones who escape the law.


Sure this doesn't represent all the entertainment industry, but even thinking that the ones who escape from this punitive licensing are a minority of this producers and filmmakers, their group origins are "affected" by that.


Many voices, victim like, are justifying the FBI action of the shutdown of megaupload to say that this place is stealing their incomings. But what about the people, with contents in megaupload without a problem of copyright that with this action are being affected? This action is affecting people with less money than the entertainment industry, but the police is not protecting them.


Furthermore, what's the cost of this international operation? Are the governments of this world expending the same number of money trying to clarify the world's bank crisis/fraud? Are this governments fighting against speculation on the markets, specially in the field of the price of the food? Although the money doesn't exist, the cost of the banks black hole is much bigger than the calculated to eradicate the world's poverty in less than one generation.


It is also ridiculous to see the public show on the TVs with images of the big house of the main boss of megaupload (how big is the house, the number of cars he have and the words he put in the plates, his eccentricities in an european cannonball, the guns he would have at home,...). But what do you expect to find in the big houses of the bosses of the entertainment and similar industries? Do they have less eccentricities? They can't reach the end of the month with their salaries?


It looks like a try to break the public image of this people. It remembers me the George Orwel's 1984. When the people was arrested, a long list of bad actions are repeated everywhere to criminalize the person.


I'm not defending, I'm only talking about the public circus created to change/manipulate opinions. This action is not to fix the problems for the common good, it's only to improve the incomings of the ones who have lots of it.

Free internet services

When a dog is bought in a pet shop, the animal has a family for free. It's like when you have a free service (as a free beer) on internet, it means that you are the product...

SOPA protest

Today is one of the days where many internet services are protesting against SOPA (Stop On-line Piracy Act) and PIPA (Protect Intellectual Property Act). In Spain there is also a similar Act under the name "ley Sinde". There are many reasons to protest to some law like this ones. 


Why the governments are acting against the intellectual property issues harder than the economical fraud?


What is worst, do not pay the contribution to the state or to referee here to hamlet:


Hamlet:
Get thee to a nunnery: why wouldst thou be a
    breeder of sinners? I am myself indifferent honest;
    but yet I could accuse me of such things that it
    were better my mother had not borne me: I am very
    proud, revengeful, ambitious, with more offences at
    my beck than I have thoughts to put them in,
    imagination to give them shape, or time to act them
    in. What should such fellows as I do crawling
    between earth and heaven? We are arrant knaves,
    all; believe none of us. Go thy ways to a nunnery.
    Where's your father? 
Hamlet, act 3 scene 1.