Mentre ero a Copenhagen un mesetto fa a presentare uno dei risultati di ATLAS da mostrare a ICHEP, in una delle pause ho comprato due copie di Voyage to the heart of Matter, che è un’altra di queste meraviglie di tecnica carto-ingegneristica e immaginazione che si sono inventati i nostri esperti di comunicazione: il libro pop-up di ATLAS! Prima di spiegarvi il perché ne ho comprato due copie, ve lo lascio ammirare: si tratta di una ingegnosa collezione di diverse rappresentazioni di ATLAS in cartoncino, da una scala più grande (tutto l’acceleratore LHC con una visione del tunnel sotterraneo) a una più piccola (l’intero rivelatore ATLAS, con persino una serie di pezzi aggiuntivi in una busta annessa, per tenere in mano veramente ogni dettaglio), accompagnate persino da una visione cartonata del Big Bang.

Se vi è venuta voglia di possedere questo bell’oggetto, sappiate che ovviamente Il libro è  in vendita, sia quaggiù al CERN che attraverso canali più consueti come Amazon. Ma torniamo alla questione dell due copie a cui accennavo prima. Una è ovviamente per me, o, se preferite, per Giulia. L’altra, beh, pensavo di regalarla a uno dei lettori del blog, per chiudere in bellezza la stagione. Che ne dite?

Ecco le regole di questo giochino estivo. Siccome questa volta il premio è un po’ più consistente del biglietto di auguri di ATLAS, per partecipare c’è da fare un po’ di lavoro, ma facile facile, promesso. Qui sotto c’è la foto di una conferenza di fisica molto famosa tenutasi nel secolo scorso (cliccate sull’immagine per una versione ingrandita), a cui parteciparono praticamente tutti i mostri sacri dell’allora nascente fisica moderna: per tentare di vincere la copia di Voyage to the heart of Matter vi propongo di provare a…

1. scoprire di che conferenza si tratta, e quando ha avuto luogo;
2. identificare chi è il fisico nella fila centrale all’estrema destra guardando la foto, quello con il circolino rosso;
3. scovate una frase qualunque detta o scritta dal suddetto fisico;

Scrivete i risultati della vostra ricerca in un commento a questo post: uno commento solo a testa, please, e citazioni del suddetto fisico non troppo lunghe (diciamo cinque righe al massimo? Insomma, non vale copiare il discorso al banchetto del Nobel. Oooops, vi ho dato un indizio. Oh beh, non che siano in molti in quella foto a non avere avuto un Nobel. O persino due). Siccome ad agosto molti sono probabilmente in vacanza, facciamo che avete tempo fino al 4 settembre. E siccome è comunque solo un gioco, ovviamente non starò troppo a fare il cane da guardia, e riterrò dunque valide anche le risposte palesemente scopiazzate da un commento precedente (se vagamente corrette, of course). Ma proprio perché è un giochino estivo, mi raccomando: non privatevi del gusto della ricerca. Il 5 settembre, che è una domenica, chiudo i commenti ed estraggo tra quanti hanno partecipato al gioco il vincitore di Voyage to the heart of Matter. Non dimenticando di lasciare nel campo ‘email’ un indirizzo reale, se volete che vi rintracci in caso siate i vincitori. Buone vacanze, ci sentiamo tra un po’!

© Marco @ Borborigmi di un fisico renitente, 31/07/2010 (Some rights reserved) | Permalink | Nessun commento (ancora)
Archiviato in: ATLAS, Fisica, Letture e scritture, Mezzi e messaggi, Scienza e dintorni | Tag: ATLAS, blog, divulgazione, gioco, interazione, libro, pop-up book

Since this is probably my last entry in this blog, I’ll entertain you with a random collection of final impressions, and maybe a tentative balance on the blogging experience itself.

The conference itself

Lot has already been said and written, so let’s simply put it this way: the conference was excellent. Superb location (Paris is always Paris), excellent venue (I was just astonished the Palais de Congres doesn’t provide wireless microphones in the smaller rooms, everything else was perfect), very efficient organization (thanks!), and an optimal balance of contents. Ok, the catering was less-then-perfect, but why should we indulge in complaining about the little details?

The LHC has entered the game

Again, not a big news, but it’s good to repeat it: we begin to see the first physics results from the LHC experiments! And even if this is not yet exciting new physics, those times are approaching fast: after more than 20 years of preparation, it’s a nice sensation for the whole community.

Experiments vs theory

On the low side, I must say that I found the theory contributions in the first part of the conference a bit isolated. This is probably normal in the context of parallel sessions (and there were anyway good phenomenological contributions in the sessions more oriented to experiment), but as an experimentalist I probably missed the opportunity to learn something really new for me. For instance, I learned from Georg that:

the talks in the lattice session had actually been selected to be accessible and of interest also to people outside the lattice community (in particular there were a number of review talks), so it was a bit of a pity that the talks were attended almost exclusively by lattice theorists.

I agree: pity! Maybe this should have been advertised more? The situation was of course different in second part of the conference, and I really appreciated some of the more theory-oriented talks in the plenary sessions.

“Sliduments” vs nice talks

The quality of the talks was in general rather good, and of course touched its best in the plenary sessions. I had anyway the impression that the non-LHC and non-Tevatron speakers gave the best talks in the parallel sessions. I have a theory, at least for the LHC talks. Nowadays we (the LHC experimental physicists) routinely use slides as a support for documentation of the daily work we are doing. Most of us have taken the (bad!) habit of packing them of all the information we want to record, information that should anyway go into a written report, sacrificing the graphical quality – and the effectiveness when used as a visual support for an oral presentation – in favor to an hybrid object that the experts in the field call slidument. Sure, it’s possibly something easier to present: one can pretend to use the text on the slide as a reminder of what to say, maybe even avoiding to reharse. Well, the quality of this kind of presentation will definitively be worse, it’s guaranteed, and – if they maybe can fit a weekly collaboration meeting – will certainly not meet the standard needed for a conference . Have a look at the slides of some of the presentations in plenary session of Wednesday, for instance the ones on dark matter or cosmology:

Almost no text, just the few word need to stress the concept, clear figure, no clutter. Sure, the speaker must now what to say on this slide! Now compare for instance with this one (taken from an ATLAS talk, so that nobody can say I’ll try to blame our competitors only):

No excuse, we have still a lot to learn!

Blogging ICHEP 2010

I am still digesting the experience, and in this sense I’d really appreciate to get some feedback by the readers on this. On my side, I can say it has been interesting to blog a conference – it was a primer for me – and to do it in a collective blog, with different voices and styles.

Some of the feedback I go tell me that the blog has been appreciated outside, especially by the colleagues that were not attending the conference: apparently it helped to feel connected, more than the webcasts and slides only can do. It might also have helped the journalists reporting the conference to the media: a blog like this can certainly act a filter, and help the non-physicist to grasp what’s important, what gets us excited, and why.

This (semi)official blog of the conference was an experiment, and in this respect the organizers wanted to keep a low profile, and verify on the field what the reactions would have been. It seems to me that, if in effect the community seems interested by the format, maybe next time something slightly more ambitious could be tried. For instance, with a bit more of organization we could have had some video interviews at the conference (someone did that, and did it very well indeed), a dedicated Twitter stream, and especially more visibility at the conference itself. I had in fact the impression that – at least at the beginning of the conference – a large part of the participants had no idea that this project was existing at all. And, since the most interesting and useful part of the blogging experience is the conversation with the readers, this could have been even more fun.

Anyway, I would probably do it again, should the occasion came. See you in two years in Melbourne?

© Marco @ Borborigmi di un fisico renitente, 30/07/2010 (Some rights reserved) | Permalink | Nessun commento (ancora)
Archiviato in: Fisica, ICHEP 2010 | Tag: blog, conferenze, ICHEP 2010, slideuments

While there are certainly good reasons to identify the French grandeur with the capital city, there is certainly more in France that just Paris. And I’m not only thinking about the food variety, that we experienced yesterday evening at the conference dinner where the excellent food specialties of five different French regions were served. Actually, that we should have experienced, and that were supposed to be served: in reality the food flow was definitively not enough to satisfy the appetite of the disappointed conference participants. But this is another story.

This valuable variety (of fine food, nice places, and of other excellent things) is rarely recognized by the Paris people – that’s a fact – but it is was rather unfortunate to discover that this point of view seems to be shared by the French President himself. As you might have heard, Nicolas Sarkozy attended the ICHEP conference yesterday to give an “opening” talk (well, the conference was opened since four days, but still). Now, I really don’t want to indulge in commenting the speech, nor I dare to discuss the subtleties of the French research politics. But I cannot refrain at least to note (at a very superficial level indeed) that both in the announcement of the President participation, and especially in the President speech, the French excellence in high energy physics seemed to be contained in circle of a 30 km radius centered on the Tour Eiffel.

I can tell you, this has definitively not pleased those ATLAS colleagues of mine working for instance in Annecy or Marseille, and I guess the other French physicist working for instance in Grenoble, or Clermont-Ferrand, or Strassbourg must not be that happy too. Oh, yes, the press office of the Elisee has finally changed the initial announcement, a now they are cited along with the other Paris university and research centers as “universités de province”, but I’m still not sure they are at ease with the classification. And, despite the last-minute change on the web site, the President speech itself was still confined to the “region parisienne”! Are the Paris people really so distracted? I would tend to doubt it, but again, this would lead me to speculate about the current French research politics, and I’m certainly not qualified for this. Pity, anyway.

© Marco @ Borborigmi di un fisico renitente, 27/07/2010 (Some rights reserved) | Permalink | 3 commenti
Archiviato in: Fisica, ICHEP 2010 | Tag: Francia, ICHEP 2010, ricerca, Sarkozy

Now we know, the Higgs boson did not show up at Tevatron. Yet.

But we also know that, if it exists, we would not find it in the 158-175 GeV mass range. The finally came to an end, certainly matching the expectation, at least for what concerns the show part. Well, as for the scientific part, after all the preliminary steps of the last days nobody was really any hint of signal anymore. We mortals might not be able to make fancy statistical combinations by eye, but it was still not too complicated to anticipate that, since there was no excess in any channel or single detector combination, we should not have expected any dramatic announcement.saga of the Tevatron Higgs talks.

I found Ben’s talk really excellent: the slides (that, by the way, were kept secret until the very last moment) were very well prepared, and Ben proved to be an excellent presenter. In a sense he was even rather humble, especially if you think about the fuss about a possible signal before the conference (at slide 46: “I’m sorry, this 2 sigma excess is the closest we have to a discovery”!).

Still – but maybe it’s just me- I had the feeling that the presentation contained a subtle innuendo. Of course Ben did not dare to say anything that was not scientifically backed, but take for instance slide 36. Ben gently dropped this CDF plot:

and casually commented: “People keeps on asking how would the exclusion plot look like if there existed a Higgs boson. We did the exercise of injecting a 115 GeV SM Higgs boson signal in several channels, and that’s what we got”. And, guess what, the results is that the exclusion curve jumps up like it had a 1 sigma fluctuation on a rather large mass range. Now, doesn’t this jump remind you of any feature we saw in another curve? There a region where the unspeakable dreams and hopes of many live, between a green and a yellow band.

© Marco @ Borborigmi di un fisico renitente, 27/07/2010 (Some rights reserved) | Permalink | 3 commenti
Archiviato in: Fisica, ICHEP 2010 | Tag: higgs, ICHEP 2010, Tevatron

Featuring Steve Myers and the status of LHC, the Spokespersons of the LHC experiments and their highlights, physicists queuing for the Presidential speech, Nicolas Sarkozy at ICHEP, the new Tevatron Higgs combination. Have fun.

© Marco @ Borborigmi di un fisico renitente, 27/07/2010 (Some rights reserved) | Permalink | 2 commenti
Archiviato in: Fisica, ICHEP 2010 | Tag: fotografia, ICHEP 2010

Not everyone is visiting Paris (but still…)

A supernova exploding in Salle Maillot

Lonely poster session

The trouble with Ultra High Energy Cosmic Rays

Preparing for the President…

© Marco @ Borborigmi di un fisico renitente, 25/07/2010 (Some rights reserved) | Permalink | Nessun commento (ancora)
Archiviato in: ICHEP 2010 | Tag: fotografia, ICHEP 2010

For instance, I was eager to attend the session on Perturbative QCD, Jets and Diffractive Physics: partly because some of the results I have been working on in the last months were presented there, partly because I wanted to know how CMS was doing on the same subject, but mainly because I wanted to know how the LHC experiments are doing on the jet measurements. Jets are in fact copiously produced in the 7 TeV LHC collisions, and even with the not huge amount of data we have collected up to not, ATLAS and CMS are in fact already capable to make nice measurements, and, in a sense, already unique ones.

I was not disappointed: Tancredi, that was presenting the jet measurements for ATLAS, opened his talk with a nice historical reminders: there was a time, nearly 30 years ago, when jets were seen for the first time at an hadronic collider (and presented in Paris!). Those were days when a physicist could get excited for a a di-jet event with a 140 GeV invariant mass, produced in hadronic collisions at a center of mass energy of 540 GeV. Today the hype is about di-jet events of 2 TeV invariant mass: it seems to me that such a comparison helps to put things into a humbling perspective, reminding us how much road has been done, how mush is still to do, and that we are all standing on the shoulders of giants.

Both ATLAS and CSM had impressive first cross section measurements for single jets and di-jet objects, already binned in different rapidity regions, and up to unprecedented di-jet masses. And the agreement with the NLO QCD theory calculation is already impressive, despite the data uncertainties are not yet the best possible!

In this particular respect, I was not completely satisfied of the way the CMS explained their approach to get the 5-10% jet energy scale they claim. They certainly have several ratio measurements that reduce the impact of the systematic uncertainty on this quantity, but I’m anyway still curious! And since the data uncertainty is still the dominant one for the cross section measurement of both experiments, and it’s mainly driven by jet energy scale, it’s a point that will become very relevant as soon at the statistics will be large enough to make precise measurements in previously unexplored and ranges. This moment is certainly not far in time!

© Marco @ Borborigmi di un fisico renitente, 24/07/2010 (Some rights reserved) | Permalink | Un commento
Archiviato in: Fisica, ICHEP 2010 | Tag: ATLAS, CMS, fotoni, ICHEP 2010, jet

Every Higgs search channel at Tevatron in has its peculiarities and its reasons of interest (since I’m working on the $H\to\gamma\gamma$ search at LHC myself, I was for instance particularly interested by this presentation), but what that I always find impressive in these session are not the single analyzes, but the combination of them.

What is rather clear in fact is that neither CDF nor D0 have enough sensitivity and data to see the Higgs (or claim it does not exist) in a single decay channel. Take for instance the $\gamma\gamma$ channel I was mentioning before: with this channel only both the Tevatron experiments can today only place a limit on the Standard Model Higgs boson production around 20 times the SM cross section.

On the other hand, this channel can add about 5% sensitivity to the combined SM Higgs combinations, and plays an especially important role in the mass region around 130 GeV. Similarly, dozens of other channels can bring their small but important contribution to the global sensitivity. Have a look for instance at the list of Higgs searches that are combined by D0:

or at the impressive combination of the CDF limits for all the channels they are looking at:

Putting all these searches together is an industrial work, with a non negligible effort of standardization of the results format, both by the different analysis teams in a collaboration and by the two collaborations. It’s something ATLAS and CMS have to learn to do quickly: as it came out during the session, there already exists a combined ATLAS-CMS effort for the statistical combination of their results, and very recently a first exercise of LHC Higgs results combination was performed, but the road to reach the current Tevatron expertise and organization is still rather long.

But – don’t you know? – the Tevatron combination will only be presented on Monday, so let’s still stick to the separated D0 and CDF ones. As you can see for the previous plot, CDF was lucky and was able to reach sensitivity to the SM at 165 GeV alone. D0 was slightly less lucky, but is nearly there too: congratulations!

The most interesting questions to the Tevatron experiments during the session were all rotating around the same subject: how much more data wold they need to bring their curves below 1 along all the mass range? It’s certainly a very relevant question: as you can see form the the ATLAS and CMS talks at the same session, the LHC experiments will need time since we can reach similar sensitivities, and in the meanwhile the Tevatron would certainly like to keep on taking data as long as possible. This is such a hot subject these days that it has percolated to the media, as the D0 speaker reminded us:

It’s certainly no easy to answer: how much would the CDF and D0 sensitivity curves would move toward 1 with twice the luminosity they have today? And with three times? Taking into account that to improve the sensitivity by a factor $N$ one needs $N^2$ the luminosity, they certainly still need quite a lot of additional data. And even if they claim they can improve the analyzes further more, and maybe include some other remote channel they might still miss in the combination, statistics will still play the dominant role. But if I were them, I would certainly try to keep on running anyway as long as I can.

© Marco @ Borborigmi di un fisico renitente, 24/07/2010 (Some rights reserved) | Permalink | 2 commenti
Archiviato in: Fisica, ICHEP 2010 | Tag: ATLAS, bosone di Higgs, CFD, CMS, D0, ICHEP 2010, Tevatron

La venuta del caro Nicolas comporta infatti che la mattina di lunedì per accedere alla conferenza dovremo presentarci con largo anticipo, e per l’occasione verranno installati controlli simili a quelli aeroportuali, metal detector compresi. Allora, immaginate un migliaio di fisici in calzoni corti e sandali (questa è la tenuta timica da queste parti, probabilmente esclusi i russi e gli indiani), ognuno rigorosamente fornito di laptop, che devono passare i controlli estraendo ognuno il suo portatile dalla borsa. Prevedo coda. E mi sa che le presentazioni del mattino subiranno qualche piccola interruzione, anche perché il caro Nicolas smuove sempre una bella folla di giornalisti (mica pensate che venga veramente a parlare a noi) che vorranno testare l’ambiente per suono e riprese ben prima. Che bello, che buona idea: proprio durante le presentazioni plenarie degli spokeperson degli esperimenti di LHC. Bof, Fabiola parla per prima, forse ATLAS se la caverà senza troppi intoppi. Forse.

Mi chiedo poi: selezioneranno quelli che possono sedere nelle prime file in base all’altezza? E Carla Bruni, verrà anche lei?

© Marco @ Borborigmi di un fisico renitente, 23/07/2010 (Some rights reserved) | Permalink | 7 commenti
Archiviato in: ICHEP 2010 | Tag: ICHEP 2010, Sarkozy

For instance: why do we get a backpack of messenger bag with the conference logo at every single conference? I mean, nowadays everyone goes to conference with her laptop bag: why should we be always came back home with two of them? And to be fair, the quality of the conference backpacks usually ranges from horrible to barely acceptable: these bags usually fall apart after a couple of months use. Conference organizers, couldn’t you spare us? Please!

For the record, this is the content of my brand new ICHEP backpack I got yesterday:

• The backpack itself! I suspect the average organizer believes that the quality of the conference is directly proportional to the number of pockets the conference bag. The ICHEP backpack has even the never-used-by-anyone cell phone pocket on the backpack strap: if my theory is correct, the conference will be a huge success.
• The conference badge. How many of them do you have at home? Do you keep them or do you trow them away? But beware, the ICHEP one might become very important in the next days (but I cannot yest tell you why)!
• The ICHEP fancy gadget: this year we got a pen that is also a laser pointer and a 2 Gb USB drive, with the conference program and booklet already loaded on. This could probably sound great, if only the gadget pen was not so over-sized to be difficult to use as… a pen.
• Paper, paper, paper. Including: the conference program, the list of participants, a issue of the CNRS magazine, a few fliers from the conference sponsors, a map of Paris, a map of the Musee de la Science, the tickets for the various social events, and even a booklet with Summer events in Paris this year.
• A weird mouse-pad (or is it a magnetic badge?) with the periodic table of elements. Who ordered that?
• A 10%-discount coupon for the Galerie Lafayette, that – as someone put it yesterday during the coffee break – is possibly the best gadget we got!

© Marco @ Borborigmi di un fisico renitente, 23/07/2010 (Some rights reserved) | Permalink | Nessun commento (ancora)
Archiviato in: Fisica, ICHEP 2010 | Tag: gadgets, ICHEP 2010