sPHENIX HCal discussion

[John Haggerty <haggerty AT bnl.gov>]

The paragraph about why we didn't use the BaBar CsI in spHENIX has 
migrated over the years from the pCDR to the CDR to the Alternatives 
Analysis 
(https://drive.google.com/open?id=0B0S-7Wbfr7kFYjg2RlB0RHhtRGs), and I 
think it would take a lot of work to argue that we could live with the 
segmenatation and timing characteristics of the CsI in heavy ions, but 
the current thought is that it might work at an EIC.  It also remains to 
show that it would be feasible, but seems more credible for EIC than 
sPHENIX.

This was the paragraph from the alternatives analysis:

> The BaBar experiment had a CsI electromagnetic calorimeter which is
> available to a new experiment.  Clearly, it is a good match
> mechanically to the BaBar solenoid, occupying radial space from about
> 90~cm to the inner radius of the cryostat, but its segmentation,
> Moli\`{e}re radius, and time resolution are not well suited to RHIC
> heavy ion operation.  The Moliere radius of the CsI(Tl) is 3.8~cm
> compared to about 2.2~cm of the proposed calorimeter, limiting the
> segmentation possible at the radius that the electromagnetic
> calorimeter could be deployed, and the segmentation reflects that,
> with the barrel divided into 48 rings of 120 crystals, compared to the
> proposed 96 rings of 256 calorimeter elements.  CsI(Tl) is a
> relatively slow scintillator, with an average decay time of about $1
> \mu s$, which would effectively integrate over 10 or more RHIC
> crossings.  Despite the attractiveness of redeploying an elegantly
> engineered and executed detector, it is not suitable for use at RHIC
> as part of a barrel calorimeter.


On 8/4/17 11:07 AM, Edouard Kistenev wrote:
> My goodness, I am not making proposals anymore, I had so many of those 
> in my 25 years at BNL (some even successful) that enough should be 
> enough. All I wanted is to attract attention to the fact (in your last 
> paragraph) that building detectors with performance on the edge of 
> “satisfying” the requirements of today provides you with no guaranties 
> for not biting your elbows tomorrow. If you can build better detector 
> without breaking the bank - do it. In case of eIC - good example are 
> jets which were nonissue for eI collisions only 5 years ago and now are 
> at the forefront.
> As for long decay times - I briefly talked to Chi of a solution proposed 
> by Haggerty - to use RC to integrate the signal (one problem is to 
> retain enough frequency range in integration not to design out the 
>   timing measurements) and use digital analysis of high frequency 
> digitization stream for CR part of the shaping. Chi pointed whole slew 
> of problems with this approach (lobut said he will give it a thought. I 
> also crossed with Sergio - he will be back from vacationing (Italy 
> !!!!!!) second week of September - ready to talk.
> Edward
>
> > On Aug 4, 2017, at 10:29 AM, Mickey Chiu <chiu AT bnl.gov 
> > <mailto:chiu AT bnl.gov>> wrote:
> >
> > Hi Edward,
> >
> > You might recognize one of the authors, a certain Jason Newby :-) 
> >  He’s a former PHENIXian.  I remember attending the intermediate 
> > neutrino workshop which was here at BNL and thinking the coherent 
> > neutrino measurement was the most interesting proposal coming out of 
> > the workshop.  Then last year I happened to bump into Jason and 
> > talking to him about the prospects, which were scientifically very 
> > good at the time.  He mentioned how difficult it was to get ORNL 
> > management to understand the value of the science, something which I 
> > could very well understand.  So it’s good to see such great science 
> > successfully coming out despite all the difficulties.
> >
> > I think one of the problems with your proposal is that you get a huge 
> > background from all the other stuff in the collision.  You’ll need to 
> > do this when there aren’t collisions, and with a strong source of low 
> > energy neutrinos.  At the very least.  I imagine you need also a very 
> > low noise readout, perhaps state of the art.
> >
> > BTW, I mentioned to JH a while back that for ePHENIX we ought to 
> > install the Babar CsI(Tl) calorimeter as a nearly ideal barrel 
> > calorimeter for the EIC that fits within the e/sPHENIX base.  The CsI 
> > crystals as you know have a slow decay so they would take a large 
> > effort to correct for the inevitable baseline shifts into tailing 
> > crossings, but the EIC rates are so low that it should not be a 
> > concern.  The resolution (sigmaE/E) is  2.3% \oplus 1.4%.  There’s a 
> > proposed requirement by Alex Kiselev that you need 5% energy 
> > resolution at the EIC, so this would satisfy it.  I note that people 
> > in PHENIX have done studies that show that 12% resolution would be 
> > good enough, and I haven’t myself verified either of these numbers. 
> >  However, it’s clear that better energy resolution should always be 
> > better, up to the lower limit that radiative effects on the primary 
> > recoil electron impose.  Anyway, JH says that he talked to the SLAC 
> > responsible person for the Babar calorimeter and the crystals are 
> > available for ePHENIX if desired.
> >
> > Mickey
> > --
> > Building 510C
> > Department of Physics
> > Brookhaven National Laboratory
> > Upton, NY 11973
> > Phone: 631-344-8428
> >
> >
> > > On Aug 4, 2017, at 9:18 AM, Edward Kistenev <kistenev AT bnl.gov 
> > > <mailto:kistenev AT bnl.gov>> wrote:
> > >
> > > Hi Xiaochun, thanks for paying attention. I know Yuri Efremenko who 
> > > found that hole under reactor but I always thought it is about 
> > > neutrinoless double beta decays, this one is very interesting too 
> > > even if neutrinos are effectively color neutral in coherent 
> > > interactions. And it will be very difficult to prove that whatever 
> > > flashes we’ll see in CsJ are not from neutrons which are plenty at 
> > > RHIC too (except for the fact that all delayed - with respect to the 
> > > bunch - flashes are from neutrons and any excess correlated with 
> > > bunch crossing could be related to production of those same neutrons).
> > > Edward
> > >
> > > On Aug 4, 2017, at 8:44 AM, Xiaochun He <xhe AT gsu.edu 
> > > <mailto:xhe AT gsu.edu>> wrote:
> > >
> > > Dear Edward,
> > >
> > > One of the authors of this project, from ORNL, is visiting GSU on the 
> > > coming Monday and Tuesday. I could ask him more details if there is 
> > > any details that you would like to know.
> > >
> > > Best,
> > > Xiaochun
> > > --
> > >
> > > Xiaochun He
> > > Distinguished University Professor
> > >  and Physics Graduate Director
> > > Department of Physics & Astronomy
> > > Georgia State University
> > > Atlanta, GA 30303
> > > ------------------------------------------------------------------------
> > > *From:*sPHENIX-HCal-l <sphenix-hcal-l-bounces AT lists.bnl.gov 
> > > <mailto:sphenix-hcal-l-bounces AT lists.bnl.gov>> on behalf of Edward 
> > > Kistenev <kistenev AT bnl.gov <mailto:kistenev AT bnl.gov>>
> > > *Sent:*Friday, August 4, 2017 8:14:49 AM
> > > *To:*sphenix-hcal-l AT lists.bnl.gov 
> > > <mailto:sphenix-hcal-l AT lists.bnl.gov>;sphenix-emcal-l AT lists.bnl.gov 
> > > <mailto:sphenix-emcal-l AT lists.bnl.gov>
> > > *Subject:*[Sphenix-hcal-l] Ever-Elusive Neutrinos Spotted Bouncing 
> > > Off Nuclei for the First Time - Scientific American
> > > Here is what we can do with BaBar CsJ if we’ll find a way to install 
> > > it and make it run in sPHENIX
> > >
> > >
> > > > https://www.scientificamerican.com/article/ever-elusive-neutrinos-spotted-bouncing-off-nuclei-for-the-first-time/ 
> > > > <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.scientificamerican.com%2Farticle%2Fever-elusive-neutrinos-spotted-bouncing-off-nuclei-for-the-first-time%2F&data=02%7C01%7Cxhe%40gsu.edu%7Cf9e319597a4a41c580d708d4db3279f3%7C515ad73d8d5e4169895c9789dc742a70%7C0%7C0%7C636374457231779086&sdata=l8VYmPYJJOHvcThBM4xtcZDcgc7hRjMGGM6Xgpfx0wA%3D&reserved=0>
> > > >
> > > >
> > > >   Ever-Elusive Neutrinos Spotted Bouncing Off Nuclei for the First Time
> > > >
> > > >
> > > >     A new technology for detecting neutrinos represents a
> > > >     “monumental” advance for science
> > > >
> > > > Juan Collar, a professor in physics at the University of Chicago, 
> > > > with a prototype of the world’s smallest neutrino detector used to 
> > > > observe for the first time an elusive interaction known as coherent 
> > > > elastic neutrino nucleus scattering./Credit: Jean Lachat / 
> > > > University of Chicago/
> > > >
> > > > Neutrinos are famously antisocial. Of all the characters in the 
> > > > particle physics cast 
> > > > <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.scientificamerican.com%2Farticle%2Fpreons-the-particle-landscape%2F&data=02%7C01%7Cxhe%40gsu.edu%7Cf9e319597a4a41c580d708d4db3279f3%7C515ad73d8d5e4169895c9789dc742a70%7C0%7C0%7C636374457231779086&sdata=mLlCFYxQbCG3TOL2vLyti0CVsuRMrKA9uDcs6kXtdX4%3D&reserved=0>, 
> > > > they are the most reluctant to interact with other particles. Among 
> > > > the hundred trillion neutrinos that pass through you every second, 
> > > > only about one per week actually grazes a particle in your body.
> > > > That rarity has made life miserable for physicists, who resort to 
> > > > building huge underground detector tanks for a chance at catching 
> > > > the odd neutrino. But in astudy 
> > > > <https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fscience.sciencemag.org%2Fcontent%2Fearly%2F2017%2F08%2F02%2Fscience.aao0990&data=02%7C01%7Cxhe%40gsu.edu%7Cf9e319597a4a41c580d708d4db3279f3%7C515ad73d8d5e4169895c9789dc742a70%7C0%7C0%7C636374457231779086&sdata=f0gOG3LZd%2Fb7OYJo5UdGEDD%2BcvK4CM%2BVWQtzS4TwDMk%3D&reserved=0>published 
> > > > today in/Science/, researchers working at Oak Ridge National 
> > > > Laboratory (ORNL) detected never-before-seen neutrino interactions 
> > > > using a detector the size of a fire extinguisher. Their feat paves 
> > > > the way for new supernova research, dark matter searches and even 
> > > > nuclear nonproliferation monitoring.
> > > > Under previous approaches, a neutrino reveals itself by stumbling 
> > > > across a proton or neutron amidst the vast emptiness surrounding 
> > > > atomic nuclei, producing a flash of light or a single-atom chemical 
> > > > change. But neutrinos deign to communicate with other particles only 
> > > > via the “weak” force—the fundamental force that causes radioactive 
> > > > materials to decay. Because the weak force operates only at 
> > > > subatomic distances, the odds of a tiny neutrino bouncing off of an 
> > > > individual neutron or proton are miniscule. Physicists must 
> > > > compensate by offering thousands of tons of atoms for passing 
> > > > neutrinos to strike.
> > > > The new experimental collaboration, known asCOHERENT 
> > > > <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsites.duke.edu%2Fcoherent%2F&data=02%7C01%7Cxhe%40gsu.edu%7Cf9e319597a4a41c580d708d4db3279f3%7C515ad73d8d5e4169895c9789dc742a70%7C0%7C0%7C636374457231779086&sdata=vjVl6iaRul2a8QAb9nEis97kU8RhfvqpQ75f0SDrKSE%3D&reserved=0>, 
> > > > instead looks for a phenomenon called CEvNS (pronounced “sevens”), 
> > > > or coherent elastic neutrino-nucleus scattering. CEvNS relies on the 
> > > > quantum mechanical equivalence between particles and waves, 
> > > > comparable to ocean waves. The high-energy neutrinos sought by most 
> > > > experiments are like short, choppy ocean waves. When such narrow 
> > > > waves pass under floating debris, they can pick out one leaf or twig 
> > > > at a time to toss around. Similarly, a high-energy neutrino 
> > > > typically picks out individual protons and neutrons with which to 
> > > > interact. But just as a long, slow wave would pick up the whole 
> > > > patch of debris at once, a low-energy neutrino sees the entire 
> > > > atomic nucleus as one “coherent” whole. This dramatically improves 
> > > > the odds of an interaction. As the number of neutrons in the nucleus 
> > > > is increased, the effective target size for the neutrino to hit 
> > > > grows in lockstep not just with that number, but with its square.
> > > > Of course, once a neutrino and a nucleus collide, the collision must 
> > > > still be detected. The neutrino bounces off and continues its 
> > > > inscrutable wandering but the nucleus also recoils slightly from the 
> > > > impact. That jolt kicks a few electrons out of their orbits around 
> > > > the nucleus and its neighbors. As the electrons fall back into 
> > > > place, they release their acquired energy as photons. Each burst of 
> > > > photons is the calling card of a neutrino.
> > > >
> > > >
> > > >     Down Neutrino Alley
> > > >
> > > > Although they are orders of magnitude more common than other 
> > > > neutrino collisions, CEvNS interactions pose formidable challenges 
> > > > to detection—so much so that no study has observed them since the 
> > > > mechanism was first theorized 43 years ago. COHERENT owes its 
> > > > success to its choices of neutrino source and target material—plus 
> > > > an unexpected assist from a cramped basement hallway.
> > > > The first problem facing COHERENT was the sheer tininess of a 
> > > > nuclear recoil. “Imagine that you take a ping-pong ball and you 
> > > > throw it at a bowling ball,” says Temple University physics 
> > > > professorJim Napolitano 
> > > > <https://na01.safelinks.protection.outlook.com/?url=https:%2F%2Fphys.cst.temple.edu%2F~napolj%2F&data=02%7C01%7Cxhe%40gsu.edu%7Cf9e319597a4a41c580d708d4db3279f3%7C515ad73d8d5e4169895c9789dc742a70%7C0%7C0%7C636374457231779086&sdata=cF3xK6YPeH7RWdHDk7NXCoVKohHLngBGQnmb7J3u030%3D&reserved=0>, 
> > > > who was not involved in the study. “We know from conservation of 
> > > > momentum [that] a little bit of energy is imparted to the bowling 
> > > > ball. This [experiment] is detecting that bowling ball’s energy”—a 
> > > > signal on the order of 10 photons.
> > > > The challenge for COHERENT, then, was to find a material with atomic 
> > > > nuclei large enough for neutrinos to hit easily, but also small 
> > > > enough that they would noticeably recoil on impact. In addition, the 
> > > > material had to be transparent so the photons could reach the 
> > > > detectors. “That took me a lot of thinking—maybe 15 years,” saysJuan 
> > > > Collar 
> > > > <https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fcollargroup.uchicago.edu%2F&data=02%7C01%7Cxhe%40gsu.edu%7Cf9e319597a4a41c580d708d4db3279f3%7C515ad73d8d5e4169895c9789dc742a70%7C0%7C0%7C636374457231779086&sdata=8VJdut%2BsBzO83ugUNyLy%2F%2B%2B1zVvNHblEin4GnUaNssg%3D&reserved=0>, 
> > > > a professor of physics at the University of Chicago and one of the 
> > > > study’s lead authors.
> > > > The second constraint was the neutrinos themselves. In theory, a 
> > > > recoil from a fast-moving neutrino would be larger, and therefore 
> > > > easier to spot—but if the neutrinos were too speedy, they would have 
> > > > too much energy to interact coherently. Eventually Collar and his 
> > > > colleagues realized that sodium-doped cesium iodine, a transparent 
> > > > crystalline material, would be an ideal target for the neutrinos 
> > > > that are produced as a by-product by the Spallation Neutron Source 
> > > > (SNS), a neutron-producing particle collider at ORNL.
> > > > <akimov1HR.jpg>SNS’s Beamline 13, which carries neutrons from the 
> > > > SNS collider to experimental stations. The same process that 
> > > > produces the neutrons also spits out neutrinos, which enter the 
> > > > COHERENT detector in the SNS basement. Credit: Jean 
> > > > Lachat/University of Chicago/
> > > >
> > > > But using the SNS as a neutrino source added a third complication. 
> > > > Neutrons can be convincing mimics of neutrinos: They have no charge, 
> > > > so they do not show up on electromagnetic detectors, and they can 
> > > > strike a nucleus with the same effects as a neutrino. When the 
> > > > COHERENT team first tested the SNS grounds, says co-author David 
> > > > Reyna of Sandia National Laboratories, they found neutrons streaming 
> > > > out of the SNS’s neutron generation site, as expected—but also 
> > > > pouring through the shielding of neighboring experimental halls. The 
> > > > detector noise from neutrons was so bad that the researchers feared 
> > > > they might not be able to use the facility at all.
> > > > Fortunately, ORNL professor of particle physicsYuri Efremenko 
> > > > <https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.phys.utk.edu%2Ffaculty%2Ffaculty-efremenko.html&data=02%7C01%7Cxhe%40gsu.edu%7Cf9e319597a4a41c580d708d4db3279f3%7C515ad73d8d5e4169895c9789dc742a70%7C0%7C0%7C636374457231779086&sdata=IyfiUmo6zNxKdj7SufH5fJ%2Bg0elGgdY0iXiMtnsG8kE%3D&reserved=0>made 
> > > > a lucky discovery: a basement hallway beneath the SNS collider. 
> > > > Despite being close to the neutron source, it happened to be 
> > > > shielded by the densely compacted earth supporting the collider’s 
> > > > many tons of concrete. After negotiations with ORNL’s safety team, 
> > > > the COHERENT team removed the empty drums that had been stored in 
> > > > the hallway and set up shop in their new “neutrino alley.”
> > > >
> > > >
> > > >     A Future Full of Neutrinos
> > > >
> > > > Experts have only glowing words for the COHERENT result. 
> > > > Massachusetts Institute of Technology physics professorJanet Conrad 
> > > > <https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fweb.mit.edu%2Fphysics%2Fpeople%2Ffaculty%2Fconrad_janet.html&data=02%7C01%7Cxhe%40gsu.edu%7Cf9e319597a4a41c580d708d4db3279f3%7C515ad73d8d5e4169895c9789dc742a70%7C0%7C0%7C636374457231779086&sdata=5T3Ri6PPrDQ3o3Mf%2B7g8KdXyo4Y4rfRN23eSYNRpYsY%3D&reserved=0>says 
> > > > she is “really, really pleased.” Napolitano calls the paper 
> > > > “monumental” and “a huge accomplishment.” And no outside expert who 
> > > > spoke with/Scientific American/expressed any technical quibbles with 
> > > > the paper. With such a convincing demonstration of the CEvNS 
> > > > phenomenon, scientists can now turn from finding it to using it.
> > > > The biggest implication is having what Collar calls a “handheld 
> > > > neutrino detector.” The compact size will be a huge boon to neutrino 
> > > > researchers; Conrad notes that one of her previous experiments had 
> > > > “mini” in its name despite being 40 feet tall. (Larger detectors 
> > > > will still be useful for studying neutrino properties that cannot be 
> > > > measured with CEvNS.) Small detectors could also eventually assist 
> > > > the International Atomic Energy Agency inmonitoring nuclear reactors 
> > > > <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.scientificamerican.com%2Farticle%2Fdetection-of-ghostly-particles-could-unmask-illicit-nuclear-weapons%2F&data=02%7C01%7Cxhe%40gsu.edu%7Cf9e319597a4a41c580d708d4db3279f3%7C515ad73d8d5e4169895c9789dc742a70%7C0%7C0%7C636374457231779086&sdata=0H7nrwTaK4RXVIFXmmx7YeibWK5ftFui%2Buc00SwZCmk%3D&reserved=0>for 
> > > > clandestine production of fuel for atomic weapons, Reyna says. The 
> > > > neutrinos pumped out by reactor cores cannot be shielded or hidden, 
> > > > so if CEvNS detectors can be adapted to spot these lower-energy 
> > > > neutrinos, inspectors could check remotely whether a reactor’s 
> > > > activities match its operators’ claims.
> > > > The CEvNS phenomenon itself also opens up new scientific frontiers. 
> > > > Collar and his colleagues are already working to test whether the 
> > > > rates of neutrino detection in different materials match theoretical 
> > > > predictions. Those same theories govern what happens in supernovae, 
> > > > which release 99 percent of their energy as neutrinos. That means 
> > > > further CEvNS experiments, in addition to detecting supernovae, 
> > > > could confirm or refute models of these colossal stellar explosions. 
> > > > And dark matter researchers are breathing a sigh of relief, because 
> > > > a close cousin of CEvNS could bolster ongoing searches for a 
> > > > hypothesized form of dark matter called weakly interacting massive 
> > > > particles (WIMPs). COHERENT’s discovery bolsters the viability of 
> > > > the WIMP theory, says Collar, and points the way to future detection 
> > > > technologies.
> > > > All these potential advances give physicists plenty to be excited 
> > > > about, says University of Michigan physicistJosh Spitz 
> > > > <https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flsa.umich.edu%2Fphysics%2Fpeople%2Ffaculty%2Fspitzj.html&data=02%7C01%7Cxhe%40gsu.edu%7Cf9e319597a4a41c580d708d4db3279f3%7C515ad73d8d5e4169895c9789dc742a70%7C0%7C0%7C636374457231779086&sdata=CwXFcaY5DauvnjVxbv2aUZZq1LMgBOckL96sg%2FmtXfs%3D&reserved=0>. 
> > > > “This [study] is just the tip of the iceberg. There’s a whole lot 
> > > > more interesting stuff to come.”
> > >
> > > _______________________________________________
> > > sPHENIX-HCal-l mailing list
> > > sPHENIX-HCal-l AT lists.bnl.gov <mailto:sPHENIX-HCal-l AT lists.bnl.gov>
> > > https://lists.bnl.gov/mailman/listinfo/sphenix-hcal-l
>
>
>
> _______________________________________________
> sPHENIX-HCal-l mailing list
> sPHENIX-HCal-l AT lists.bnl.gov
> https://lists.bnl.gov/mailman/listinfo/sphenix-hcal-l


--
John Haggerty
email: haggerty AT bnl.gov
cell: 631 741 3358