Benedetto D'Ettorre Piazzoli（意大利） 

　　那不勒斯大學(xué)教授， 

　　ARGO-YBJ實(shí)驗(yàn)意方發(fā)言人， 

　　意大利國(guó)家核物理研究院前副主席  

　　The exciting news is the LHAASO detection of more than 530 extensive air showers  generated by Ultra High Energy  photons coming from the direction of 12  galactic sources . Since gamma rays propagate straight , this detection indicates the direction of the cosmic ray factories accelerating cosmic rays to one million of giga-electronvolt energies or more, the so-called PeVatrons, whose nature puzzled scientist for long time. 

　　 [ Indeed, gamma rays of such energies cannot be produced thermally, they are generated when highly relativistic cosmic rays collide with ambient gas, as, for instance, molecular clouds.] 

　　I would like to comment the  reason of the LHAASO performance . 

　　Two aspects are relevant in this context :  a challenging project and technical design and its efficient realization at high altitude requiring an adequate organization. 

　　The LHAASO layout consists of an impressive assembly of many traditional instruments equipped with advanced technology  devices . The combination of ‘brute force’ and technology at the edge of that currently available  gives LHAASO an outstanding and unprecedented sensitivity to detect high-energy gamma rays. 

　　Experimental conditions at the top of the mountain at an altitude of 4410 meters are challenging. Persons have to withstand  harsh conditions often troublesome for humans. Yet setting-up experimental apparatus in remote locations can still be fraught with logistic difficulties. 

　　I visited the LHAASO site 2 years ago. Despite the apparent remoteness , Daocheng hosts reasonable infrastructures and communications. A small village 1-hour distant by car at a lower altitude operates as a base hosting a guest-house , living and dining and  working facilities . Careful planning has been critical to ensure a regular installation and operation. As a result, LHAASO is growing according to the time schedule and will be completed in this year. 

　　LHAASO will operate continuously and steadily for many years in order to accumulate a large data set . While extending the search for PeVatrons, LHAASO will explore in depth a wide energy range where the transition from galactic to extragalactic cosmic rays is expected , a region covered by very few experiments. Many of  LHAASO discoveries will no doubt bring surprises.  Thus, there is a good chance that the cosmic-ray mystery  could be unveiled. There are exciting times ahead.
 

　　LHAASO探測(cè)到了從12個(gè)超高能伽馬源輻射而來(lái)的530多個(gè)空氣簇射事例，這是一個(gè)令人興奮的消息。 因伽馬射線沿直線傳播，這些事例瞄準(zhǔn)了十幾個(gè)宇宙線加速工廠的方向。 這些工廠把宇宙線加速到了1000萬(wàn)億電子伏特甚至更高的能量，稱為所謂的拍電子伏特加速器（英文名稱：PeVatrons），其性質(zhì)長(zhǎng)期以來(lái)一直困擾著科學(xué)家。 

　　[確實(shí)，具備如此高能量的伽馬射線不可能起源于熱輻射，它們是由極端相對(duì)論的宇宙線與周圍氣體例如分子云碰撞產(chǎn)生的。] 

　　下面我對(duì)LHAASO的優(yōu)良性能做一點(diǎn)評(píng)價(jià)。 

　　LHAASO的成功可以歸結(jié)為兩個(gè)方面的原因：挑戰(zhàn)性的工程設(shè)計(jì)，及其在高海拔地區(qū)高效地實(shí)現(xiàn)。這兩個(gè)方面都離不開(kāi)完善的組織與協(xié)調(diào)。 

　　LHAASO陣列-由極其大量的傳統(tǒng)探測(cè)器組成，但它們都配備了先進(jìn)的技術(shù)設(shè)備。 “暴力”解決方案與尖端技術(shù)的結(jié)合，賦予了LHAASO卓越的、前所未有的高能伽馬探測(cè)靈敏度。 

　　在4410米的高山之巔開(kāi)展實(shí)驗(yàn)極具挑戰(zhàn)性，人們必須克服惡劣的自然條件給身體帶來(lái)的許多麻煩，在偏遠(yuǎn)地區(qū)安裝儀器設(shè)備還存在著許多后勤方面的困難。 

　　兩年前我訪問(wèn)了LHAAO站址。盡管距離遙遠(yuǎn)，稻城卻擁有不錯(cuò)的基礎(chǔ)設(shè)施和通訊。在這個(gè)小城鎮(zhèn)里運(yùn)營(yíng)著一個(gè)具備住宿、生活、餐飲和工作等相關(guān)設(shè)施的測(cè)控基地，距離觀測(cè)站僅僅1小時(shí)車程，海拔也較低。 這些周密的考慮和安排對(duì)于確保正常的探測(cè)器安裝和運(yùn)行至關(guān)重要，正因?yàn)槿绱耍?/span>LHAASO按照時(shí)間表穩(wěn)步推進(jìn)，將在今年內(nèi)建成。 

　　LHAASO將持續(xù)穩(wěn)定運(yùn)行多年，積累大量的數(shù)據(jù)。在擴(kuò)大搜索PeVatron的同時(shí)，LHAASO將在寬廣的能量范圍內(nèi)深入探索宇宙線從銀河系內(nèi)起源向銀河系外起源的轉(zhuǎn)換，這個(gè)領(lǐng)域其實(shí)并未開(kāi)展過(guò)充分的實(shí)驗(yàn)研究。 LHAASO將會(huì)帶來(lái)許多驚喜的發(fā)現(xiàn)，宇宙線起源之謎有機(jī)會(huì)被揭開(kāi)，未來(lái)定會(huì)有一些激動(dòng)人心的時(shí)刻。